# PC2-4200,5300,6400: Whats the difference? Same in price



## TechShark

I was on www.crucial.com

Looking to buy some more memory for my Mobo http://www.newegg.com/Product/Product.aspx?Item=N82E16813135062

It has 4 slots, 
2 with matching pair, 2x 1g ram, and then another 1g. and on empty total 3 g of ram.

im looking to a buy another matching pair to replace my 1g, and put on in the empty slot

but i came across pc2-4200, 5300, 6400 for all the same price on crucial.. is one better than the other?


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## oscaryu1

Same price?! Go for the highest your motherboard can support!

Dumbed down, the higher the number, the faster the RAM.


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## PC eye

That model supports DDR2 800 PC2-6400 memory as the fastest speed. The thing to look at before ordering is what memory you already have installed as far as speed and type. 

You don't want to mix performance memory if you are running standard or value ram presently. If you have 2gb of DDR2 533 another 2gb of DDR2 800 would see the faster 800 slowed to 533mhz. When going to replace the 3rd 1gb dimm you want to match as closely as possible or replace the first 2gb in preference of seeing a faster memory.


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## TechShark

So i checked what i have  its, 2x1gb Corsair Twinx (XMS) Heat Shield DDR2 PC2-6400 800mhz, So i should get another pair of the 6400?


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## diduknowthat

Best get another pair of the same ram. Mix and matches can sometimes lead to trouble.


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## PC eye

That's the DDR2 800 performance memory by Corsair there. Corsair is a good brand to start off with plus you wouldn't want to mix another brand's pair and see a difference in timings.

When going to order one thing to note is that are different 2gb kits of the xms series memory to choose from. Those will also see differences in timings and voltages plus there's a Dominator version. http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=2000170147%2050001666%201052108080%201052416064%201052308477&name=2GB%20%282%20x%201GB%29

You'll want to match what you have now with the correct pair chosen from the several kits at the link there.


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## TechShark

The link you sent me was very helpful PcEye thank you.
How can i figure what timing is mine?

i checked inside my tower and i have either one of these, they look identical. just dont know what timing mine is

http://www.newegg.com/Product/Produ...mpareItemList=N82E16820145034,N82E16820145590


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## PC eye

That was partly my fault there having forgotten to mention a freeware called CPU-Z that will show the timings as well as the frequency the memory is operating at.  http://www.cpuid.com/pcwizard.php

Now don't get alarmed when seeing something like what is in the image here as far as the frequency is concerned. While listed as 800 you have to add the multiplication factor of "2" when looking at that with what CPU-Z shows. That how DDR, DDR2, DDR3 memory works.





Think of a single lane road being widened for a second lane to understand doubling the bandwidth.


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## TrainTrackHack

> Think of a single lane road being widened for a second lane to understand doubling the bandwidth.


That is called dual-channeling. DDR memory doesn't double the actual bandwidth; the bandwidth remains 64-bit (or 128-bit for dual-channel). DDR simply doubles the number of transfers per clock from 1 to 2, hence the name *D*ouble (or *D*ual) *D*ata *R*ate.



> you have to add the multiplication factor of "2"


There's no such thing as a "multiplication factor" as far as mathematics are concerned.


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## StrangleHold

PC eye said:


> Now don't get alarmed when seeing something like what is in the image here as far as the frequency is concerned. While listed as 800 you have to add the multiplication factor of "2" when looking at that with what CPU-Z shows. That how DDR, DDR2, DDR3 memory works.
> 
> 
> 
> 
> 
> Think of a single lane road being widened for a second lane to understand doubling the bandwidth.


 
 DDR
PC eye you have been told this hunderds of times. DDR is not like a 2 lane road. DDR2 800 runs at 400mhz period. Unlike plain SDRAM, DDR can transfer data on the rising and falling of a single clock cycle. There is no second lane. It just has the capability of transfering twice the amount of data then plain SDRAM. The only reason its referred to as 800 is it would take a plain SDRAM stick of memory running at 800mhz to tranfer the same amount of data.


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## tyttebøvs

StrangleHold said:


> DDR2 800 runs at 400mhz period.



Not if you overclock it


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## StrangleHold

tyttebøvs said:


> Not if you overclock it


 
Yea a few weeks ago, cant remember exactly how it went, (pretty close). DDR2 800 was two sticks running at 400 + dual channel, so two channels at 400mhz = 800mhz. I was in amazement, laughed so hard my right eye went bloodshot.


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## porterjw

You obviously misinterpretted what PC meant, like all of us do all the time someone proves him wrong



> laughed so hard my right eye went bloodshot.



Heh.


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## gamerman4

tyttebøvs said:


> Not if you overclock it



if you overclock it then it will no longer be DDR2-800 then would it?
it would be DDR2-[insert new overclocked speed]



> You obviously misinterpretted what PC meant, like all of us do all the time someone proves him wrong



I second that, he has decent information but he loves using the verb "see" in almost every sentence which is epic fail when you are trying to actually understand him.


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## porterjw

> I second that, he has decent information



Now my right eye just went bloodshot...

I'm not sure ya fully understood the hidden sarcasm in my last Post.


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## gamerman4

> Now my right eye just went bloodshot...



Might want to get that checked out... 



imsati said:


> I'm not sure ya fully understood the hidden sarcasm in my last Post.



i know what you meant but I don't believe his information sucks all the time, just most of the time so "decent" is a crappy enough word to fit without actually claiming his info completely sucks all of the time.


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## tyttebøvs

gamerman4 said:


> it would be DDR2-[insert new overclocked speed]



Should that be multiplied by two, or ...?


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## gamerman4

tyttebøvs said:


> Should that be multiplied by two, or ...?



DDR2-800 has a memory clock speed of 200mhz and an I/O bus clock speed of 400mhz (what Stranglehold mentioned)

Overclocking a CPU FSB also overclocks the internal RAM clock speed.

CPU: (ill use mine as an example) Q6600
advertised FSB = 1066mhz
base FSB = 266mhz
multiplier = 9
clock speed= 2400mhz

this translates into RAM as
base FSB of CPU = memory clock speed of RAM (when using a 1:1 divider)
so
266mhz FSB = 266mhz memory clock
266FSB translates into 1066mhz FSB so you would need DDR-1066
a 200mhz FSB would need DDR2-800

so to answer your question when you see DDR2-800 you divide the "800" by 4 to get the base clock speed. This helps when overclocking because it is best to run your RAM at the same base clock as your CPU FSB.

Once you overclock it is no longer DDR2-800 but rather a higher speed.


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## TechShark

Jeez, I know a fair amount of information above the average computer user but you guys a running circles around me haha. I checked my timing with the cpu-z. it is the 5-5-5-18. 
I currently have a total of 4 slots, 1 is open. 2 have the corsair memory mentioned earlier. and one slot has some different brand of 1g memory. I'm going to remove the 1g and replace it with 2 of the same corsair memory of 5-5-5-18 timing. Will this be a good decision for optimum performance?


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## gamerman4

TechShark said:


> Jeez, I know a fair amount of information above the average computer user but you guys a running circles around me haha. I checked my timing with the cpu-z. it is the 5-5-5-18.
> I currently have a total of 4 slots, 1 is open. 2 have the corsair memory mentioned earlier. and one slot has some different brand of 1g memory. I'm going to remove the 1g and replace it with 2 of the same corsair memory of 5-5-5-18 timing. Will this be a good decision for optimum performance?



The timing doesn't make a huge difference but having two sticks of RAM will give you the benefit of running dual channel which will increase your performance beyond what the timings are but you will have less RAM so you are going to have to ask yourself if you need more RAM or more memory bandwidth, I would just go with keeping the 3 sticks, dual channel doesn't make a huge difference either. I have 2 sticks and tried them in single and dual channel with only a difference between 5.0 and 5.3 on the Vista Exp. Index. Of course, you could always just try it yourself and take one stick out, and run some benchmarks. You might benefit from the extra bandwidth in dual channel if you play games that don't need past 2GB of RAM but if you do things like video editing then more RAM will be better than higher bandwidth.


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## Mitch?

yes that sounds like a good idea, just find the corsair pack that have similar timings (if the timings are too low, say the new ones you buy are lower than the ones you have, they'll just move to 5-5-5-18 anyway)



			
				Gamerman said:
			
		

> The timing doesn't make a huge difference


Timings make a significant difference. If he's using his ram to it's fullest now, tightenin the timings to 4-4-4-15 will make a difference.
I got 250 3dmark06 points, just by bringing my ram to 4-3-4-12 @ DDRII800.


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## gamerman4

Mr. Johanssen said:


> yes that sounds like a good idea, just find the corsair pack that have similar timings (if the timings are too low, say the new ones you buy are lower than the ones you have, they'll just move to 5-5-5-18 anyway)
> 
> 
> Timings make a significant difference. If he's using his ram to it's fullest now, tightening the timings to 4-4-4-15 will make a difference.
> I got 250 3dmark06 points, just by bringing my ram to 4-3-4-12 @ DDRII800.



250 more points is by far not even slightly what I would call "significant" when points are measured up in the thousands. Also, tightening timings is more for advanced overclockers because it takes some practice and a large understanding of what the timings do and how they relate to eachother in order for them to work well. Often lower timings cause more failed POSTs than just raising the bandwidth, it is easy to get your RAM unstable with tight timings. I usually just raise timings in order to keep my RAM running at a 1:1 ratio, if it is already at 1:1 then I just keep timings at default. Lower timings mean nothing when your RAM is not at 1:1 with you CPU.


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## Mitch?

gamerman4 said:


> 250 more points is by far not even slightly what I would call "significant" when points are measured up in the thousands. Also, tightening timings is more for advanced overclockers because it takes some practice and a large understanding of what the timings do and how they relate to eachother in order for them to work well. Often lower timings cause more failed POSTs than just raising the bandwidth, it is easy to get your RAM unstable with tight timings. I usually just raise timings in order to keep my RAM running at a 1:1 ratio, if it is already at 1:1 then I just keep timings at default. Lower timings mean nothing when your RAM is not at 1:1 with you CPU.



depending on his cpu, it may be at 1:1, at 3.2ghz cpu my ram runs 400mhz, and 250 does matter, considering it doesn't help the video card (as my cpu bottlenecks it), thats 250 CPU points, where it'd a fair increase.


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## gamerman4

Mr. Johanssen said:


> depending on his cpu, it may be at 1:1, at 3.2ghz cpu my ram runs 400mhz, and 250 does matter, considering it doesn't help the video card (as my cpu bottlenecks it), thats 250 CPU points, where it'd a fair increase.



I'll agree with a "fair" increase but not significant.


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## Mitch?

gamerman4 said:


> I'll agree with a "fair" increase but not significant.



ha ok


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## gamerman4

Mr. Johanssen said:


> ha ok



lol
I also want to add 3dmark isn't the best way to bench CPU/RAM speeds (as I'm sure you already know). I like SiSoft Sandra (freeware version is fine), it has extensive benchmarking and a lot better info than just a black and white number score.


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## TechShark

Thank for the info. But i meant like...heres my exisiting set up 
( Slot 1)    ( Slot 2 )        ( Slot 3 )             (slot 4)
 Corsair       Corsair   (Non matching 1 g)       Empty

i want to replace slot 3 and 4 with the same corsair pc2-6400 800mhz timing 5-5-5-18 memory. 
and was seeing if that would be the optimal choice. for highest performance?

and another thing, If someone could explain to me.....

what "Exactly" (or closest to exactly) do the timing numbers mean? #-#-#-# ?

and why are they in the format of 3 numbers and one large one?
Thanks again, I really appreciate all this info. I still have a lot to learn..0_o


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## gamerman4

if you are going to have 4 of the same corsair mem, well of course that would be better, more RAM and dual channel (if your mobo supports 4 RAM sticks in dual channel). The non-matching stick would possibly causes issues in dual channel.


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## StrangleHold

gamerman4 said:


> i know what you meant but I don't believe his information sucks all the time, just most of the time so "decent" is a crappy enough word to fit without actually claiming his info completely sucks all of the time.


 
I'm seriously thinking of using that as a signature


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## TrainTrackHack

> DDR2-800 has a memory clock speed of 200mhz and an I/O bus clock speed of 400mhz (what Stranglehold mentioned)
> 
> Overclocking a CPU FSB also overclocks the internal RAM clock speed.
> 
> CPU: (ill use mine as an example) Q6600
> advertised FSB = 1066mhz
> base FSB = 266mhz
> multiplier = 9
> clock speed= 2400mhz
> 
> this translates into RAM as
> base FSB of CPU = memory clock speed of RAM (when using a 1:1 divider)
> so
> 266mhz FSB = 266mhz memory clock
> *266FSB translates into 1066mhz FSB so you would need DDR-1066
> a 200mhz FSB would need DDR2-800*
> 
> so to answer your question when you see DDR2-800 *you divide the "800" by 4 to get the base clock speed.* This helps when overclocking because it is best to run your RAM at the same base clock as your CPU FSB.
> 
> Once you overclock it is no longer DDR2-800 but rather a higher speed.


Wrong. Firstly, FSB is quad-pumped (or quad data rate), so a 266MHz FSB effectively runs at 1066MTs. However, DDR RAM is dual-pumped (or double/dual data rate), so 266MHz DDR(2) RAM effectively runs at 533MTs. Therefore, when using 1:1 divider, 1066 FSB should be paired with DDR2-533.

And as I said, since DDR memory is double/dual data rate (or dual pumped, whichever term you wish to use), you divide the AAA in DDR(X)-AAA by 2 to get the clockspeed; you divide by four only if something's quad-pumped (/quad data rate), such as FSB.


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## tyttebøvs

The confusion might lie in the fact that the internal (chip) speed of DDR2 is half the speed of the external bus. So to get that, you divide by 4. But since it is all internal, it is rather irrlevant in these calculations.


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## StrangleHold

TechShark said:


> Thank for the info. But i meant like...heres my exisiting set up
> ( Slot 1) ( Slot 2 ) ( Slot 3 ) (slot 4)
> Corsair Corsair (Non matching 1 g) Empty
> 
> i want to replace slot 3 and 4 with the same corsair pc2-6400 800mhz timing 5-5-5-18 memory.
> and was seeing if that would be the optimal choice. for highest performance?
> 
> and another thing, If someone could explain to me.....
> 
> what "Exactly" (or closest to exactly) do the timing numbers mean? #-#-#-# ?
> 
> and why are they in the format of 3 numbers and one large one?
> Thanks again, I really appreciate all this info. I still have a lot to learn..0_o


 

Yes, getting the same 555-18 would be your best bet, having them all the same. But the 555-15 would not hurt anything, if its the same voltage the timing is just off by a small margin and would backclock to 18 anyway if set to auto. As far as what they mean. A short version.

CAS - You could look at it like the delay time in a cycle.
tRCD - The time in a cycle to active a command.
tRP - How long it takes to swap memory banks.
tRAS - the amount of time between being precharged and deactivated


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## gamerman4

hackapelite said:


> Wrong. Firstly, FSB is quad-pumped (or quad data rate), so a 266MHz FSB effectively runs at 1066MTs. However, DDR RAM is dual-pumped (or double/dual data rate), so 266MHz DDR(2) RAM effectively runs at 533MTs. Therefore, when using 1:1 divider, 1066 FSB should be paired with DDR2-533.
> 
> And as I said, since DDR memory is double/dual data rate (or dual pumped, whichever term you wish to use), you divide the AAA in DDR(X)-AAA by 2 to get the clockspeed; you divide by four only if something's quad-pumped (/quad data rate), such as FSB.



ummm.....http://en.wikipedia.org/wiki/DDR2_SDRAM
read the chart but here is a quote



> Like all SDRAM implementations, DDR2 stores memory in memory cells that are activated with the use of a clock signal to synchronize their operation with an external data bus. Like DDR before it, DDR2 cells transfer data both on the rising and falling edge of the clock (a technique called "double pumping"). The key difference between DDR and DDR2 is that in DDR2 the bus is clocked at twice the speed of the memory cells, so four bits of data can be transferred per memory cell cycle. Thus, without speeding up the memory cells themselves, DDR2 can effectively operate at twice the bus speed of DDR.



so DDR2 is double pumped and twice the clock speed at the bus but the internal speed equals the CPU FSB (on a 1:1 ratio).

if FSB = 266mhz then DDR2 RAM = 266mhz internal
Core2s are quad-pumped while DDR2 is double pumped while running at double the rate of DDR so

266FSB quadpumped = 1066FSB
and
266mhz mem clock double pumped with double clock = 1066mhz.


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## TrainTrackHack

> so DDR2 is double pumped and twice the clock speed at the bus but the internal speed equals the CPU FSB.
> 
> *FSB = 266mhz then DDR2 RAM = 266mhz internal*
> Core2s are quad-pumped while DDR2 is double pumped while running at double the rate of DDR so
> 
> 266FSB quadpumped = 1066FSB
> 
> 266mhz mem clock double pumped with double clock = 1066mhz.


Like tyttebovs said, the internal clockspeed doesn't matter (since it's half of the external speed and that can't be changed). The memory bus clockspeed is still the same as FSB clockspeed when the divider is set to 1:1. DDRn RAM is rated at double the external clockspeed, or the bus speed; hence, the rating of *Dual* Data Rate RAM should be half of the rating of the *Quad* Data rate FSB. Since I'm a nice boy P), I bolded the incorrect part for you; as I said, the _external_ memory clock is the one that runs in sync with the FSB when the divider is set to 1:1. The internal clock speed, in your example, would be the half of the external clock, or 133MHz, whereas you seem to think that when the divider is 1:1 the FSB the _internal_ clockspeed of the RAM will be synced with the FSB - this is incorect.

From wikipedia: http://en.wikipedia.org/wiki/Pumping_(computer_systems)


> Example: A Core 2 Duo E6600 processor is listed as 2.4 GHz with a 1066 MHz FSB. *The FSB is known to be quad-pumped, so its true frequency is 266 MHz.* Therefore, the CPU multiplier is 9×. *The DDR2 RAM that it is compatible with is known to be double-pumped, so to run the system synchronously (see Front side bus) the type of RAM that is appropriate is double 266 MHz, or DDR2-533.*


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## TechShark

Not sure if i'm getting this completely right but,  when it comes to the numbers "#-#-#-#" or my "5-5-5-18" the smaller the number the better?

being that the transfer rate is faster? err i think right?


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## TrainTrackHack

> Not sure if i'm getting this completely right but, when it comes to the numbers "#-#-#-#" or my "5-5-5-18" the smaller the number the better?
> 
> being that the transfer rate is faster? err i think right?


Yes, lower timings are better; lower timings simply decrease the latency i.e. the time it takes before the CPU will actually get the data it requested, but doesn't really affect the speed (the throughput remains the same regardless of timings).


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## tyttebøvs

hackapelite said:


> (the throughput remains the same regardless of timings).



About throughput. I would think that the delay in time between commands and how long a command takes to execute will affect the overall throughput.


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## TrainTrackHack

> About throughput. I would think that the delay in time between commands and how long a command takes to execute will affect the overall throughput.


In theory, throughput will remain same regardless of timings, since timings simply specify how many clock cycles it takes to retrieve data - even if the timings are set higher, the memory can still handle the same number of transfers as before providing that the clockspeed doesn't change. However, in practice performance will suffer since the CPU has to wait longer for the data, and while waiting it will pretty much sit idle meaning that there are no memory I/O operations, hence the available bandwidth will not be utilized.


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## tyttebøvs

In theory, there will also be no data on the bus while the ram prepares for data to be transfered. Increase the delay and less data will be transfered over time.


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## TrainTrackHack

> In theory, there will also be no data on the bus while the ram prepares for data to be transfered. Increase the delay and less data will be transfered over time.


I'm not sure what you mean here... if DDR memory runs at 800MTs, it _can_ (in theory) perform 800 million transfers per second, regardless of timings; the RAM can accept commands at a rate specified by effective clockspeed while other data is being prepared for transfer.


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## tyttebøvs

You have: command(s), data on the bus, command(s), data on the bus, command(s), ...

So the delay between data on the bus affects how much data you get through


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## StrangleHold

Timing will effect the amount of data the CPU receives in a certain time regardless of the mhz. its running at.

 I,m going to go stupid noob and use cars. Cars on two different roads. All going 30mph. If the red lights last a fraction of a second longer on the first road, then there will be more cars get to the other end on the second road faster. Doesnt matter if all cars were traveling at 30mph.


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## scooter

StrangleHold said:


> Timing will effect the amount of data the CPU receives in a certain time regardless of the mhz. its running at.
> 
> I,m going to go stupid noob and use cars. Cars on two different roads. All going 30mph. If the red lights last a fraction of a second longer on the first road, then there will be more cars get to the other end on the second road faster. Doesnt matter if all cars were traveling at 30mph.



What type of cars are on the road...

some accelerate faster....say there was like 15 yugos and 1 lamborghini...


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## StrangleHold

scooter said:


> what type of cars are on the road...
> 
> Some accelerate faster....say there was like 15 yugos and 1 lamborghini...


 
lol


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## gamerman4

hackapelite said:


> Like tyttebovs said, the internal clockspeed doesn't matter (since it's half of the external speed and that can't be changed). The memory bus clockspeed is still the same as FSB clockspeed when the divider is set to 1:1. DDRn RAM is rated at double the external clockspeed, or the bus speed; hence, the rating of *Dual* Data Rate RAM should be half of the rating of the *Quad* Data rate FSB. Since I'm a nice boy P), I bolded the incorrect part for you; as I said, the _external_ memory clock is the one that runs in sync with the FSB when the divider is set to 1:1. The internal clock speed, in your example, would be the half of the external clock, or 133MHz, whereas you seem to think that when the divider is 1:1 the FSB the _internal_ clockspeed of the RAM will be synced with the FSB - this is incorect.
> 
> From wikipedia: http://en.wikipedia.org/wiki/Pumping_(computer_systems)




Alright that's fine, your argument is agreeable, I must have just misunderstood the wiki article at first. Thanks for clearing that up. I learned about overclocking when I had an AMD CPU and the old Athlon 64s were also double-pumped.

Here is how I got confused:

My motherboard uses the internal clock as designated by the SPD of the RAM in order to do it's calculations.
The minimum RAM multiplier is 2.66 which is actually a .66 divider with the inevitable double-pumping added in there to simplify things.
The 1:1 ratio is actually a 2:1 RAM:CPU ratio since DDR2 has to run at twice the clock speed of DDR to make up for the increased latency.
My motherboard shows the maximum multiplier at 4x which is the 2:1 ratio (2 for double-pumping and 2 for double the rate)
My confusion was in that my motherboard actually uses the 200mhz internal clock of DDR2-800 (266 internal for 1066) and just combines both the double-pumping (which cannot be changed) and the data rate (which can be changed)

here is how I assume my motherboard calculates the clocks for memory:
*(CPU FSB) x (2 + [data rate multiplier])*
the 2 is constant because you cannot change the fact that it is double-pumped and the data rate multiplier is like a RAM divider.

So I was confusing a 1:1 ratio with what was actually a 2:1 ratio


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## tyttebøvs

The SPD doesn't list the internal/chip speed. It lists the speed in which the ram module talks to the outside world.

The internal speed is only relevant, if you look at how the module is constructed. What is relevant is how the bus between the module and memory controller works. And this bus is double pumped.

Also remember that the latency numbers are relative to how fast the bus is running. A "5" takes longer at 200Mhz than it does at 400Mhz


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## gamerman4

tyttebøvs said:


> The SPD doesn't list the internal/chip speed. It lists the speed in which the ram module talks to the outside world.
> 
> The internal speed is only relevant, if you look at how the module is constructed. What is relevant is how the bus between the module and memory controller works. And this bus is double pumped.
> 
> Also remember that the latency numbers are relative to how fast the bus is running. A "5" takes longer at 200Mhz than it does at 400Mhz



ok then could you explain why the motherboard multiplies by 4 to get 800mhz for my RAM from an FSB set to 200mhz?


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## StrangleHold

Its not, its multiplied by 2. The memory is running at 400mhz. You can say 800mhz because of the memory being DDR itself but theoredically its running at 400mhz.


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## gamerman4

StrangleHold said:


> Its not, its multiplied by 2. The memory is running at 400mhz. You can say 800mhz because of the memory being DDR itself but theoredically its running at 400mhz.



But why would the BIOS say memory multiplier: 4

I was looking around the subject and here is what THG states

"A 3.73 GHz Pentium 4 Extreme Edition processor was our chosen chip, because it works with the system clock set to 266 MHz to produce FSB1066; with a 1:1 FSB/memory ratio, that also means the memory runs at DDR2-1066."
This would mean my statement was true and that in a 1:1 ratio a 266 chip is not DDR2-533 (which when divided by 2 would equal 266) but rather DDR2-1066."
The P4EEs are also quad-pumped so they are no different than a Core2 in the situation.


CPU-Z of DDR2-1066






it shows that the frequency is roughly 1066/4


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## tlarkin

tyttebøvs said:


> You have: command(s), data on the bus, command(s), data on the bus, command(s), ...
> 
> So the delay between data on the bus affects how much data you get through



Yup it is just more bandwidth (more data throughput) really.  The throughput you can put on your RAM means the faster instruction sets can be placed and paged from RAM.

Does it make a difference?

yes if you push your machine to use more bandwidth.  It can also create a bottle neck if it is moving too fast for the rest of your system.  You are only as fast as your slowest component, which is almost always the hard drive.


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## StrangleHold

gamerman4 said:


> But why would the BIOS say memory multiplier: 4
> 
> I was looking around the subject and here is what THG states
> 
> "A 3.73 GHz Pentium 4 Extreme Edition processor was our chosen chip, because it works with the system clock set to 266 MHz to produce FSB1066; with a 1:1 FSB/memory ratio, that also means the memory runs at DDR2-1066."
> This would mean my statement was true and that in a 1:1 ratio a 266 chip is not DDR2-533 (which when divided by 2 would equal 266) but rather DDR2-1066."
> The P4EEs are also quad-pumped so they are no different than a Core2 in the situation.
> 
> 
> CPU-Z of DDR2-1066
> 
> 
> 
> 
> 
> it shows that the frequency is roughly 1066/4


 
I dont know any other way to explain it to you. The Screenshot looks like a stick of 512mb. DDR2 533 overclocked a couple of mhz. Memory is not Quad pumped.


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## gamerman4

StrangleHold said:


> I dont know any other way to explain it to you. The Screenshot looks like a stick of 512mb. DDR2 533 overclocked a couple of mhz. Memory is not Quad pumped.



Having never said that DDR is quad-pumped, here is my explanation.

I'm going to go back in time for a sec to DDR...

DDR RAM:
-your FSB dictated exactly your memory clock speed (AFAIK the memory, not the bus)
-so a 200mhz FSB would mean 200mhz memory clock
- DDR is double pumped so that 200mhz mem clock means 400mhz at the bus
-this equated to DDR-400

DDR2 RAM:
-your FSB still dictates your mem clock
-200mhz FSB means 200mhz mem clock
-DDR is double pumped so it is a base of 400mhz at the bus
-the DDR2 bus operates twice as fast as a DDR bus so that 400mhz operates at 800mhz, giving DDR2-800

Based on all the evidence I have found, I am convinced that the memory clock, not the bus clock, is what changes with your clock speed.

Now if you could find somewhere that states that it is the bus and not the memory clock that gets modified by your CPUs FSB then I will try to recreate my hypothesis in favor of the new data. So far I stand by my original statement.


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## StrangleHold

No, just because something it double or quad pumped does not mean that the bus runs at that mhz. If we are talking about a (1:1). If you have a 266 FSB quad pumped/1066 the bus is still running at 266. So a 1:1 with memory would be running DDR2 533 because both base clocks are running at 266.


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## gamerman4

StrangleHold said:


> No, just because something it double or quad pumped does not mean that the bus runs at that mhz. If we are talking about a (1:1). If you have a 266 FSB quad pumped/1066 the bus is still running at 266. So a 1:1 with memory would be running DDR2 533 because both base clocks are running at 266.



that would apply to DDR RAM, DDR2 has a bus that runs twice as fast as a DDR bus, therefore it further doubles the double-pumped rate.


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## StrangleHold

I think your getting mixed up between the External clock speed and the Data bus speed, DDR2 533 has a External clock speed of 266mhz but has a Data bus speed of 533 Mbps. DDR2 has 4 bit prefetch where DDR has 2 bit.


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## gamerman4

DDR2-533 may have an external bus clock of 266 but it has an internal memory clock of 133.

I am pretty sure overclocking relies on the internal memory clock as its base. 
Also that CPU-Z pic was of DDR-1066, not 533, regardless of being dual or quad pumped, it runs 4 times as fast as its base speed because of 2 different factors, the bus speed and the double data rate.


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## StrangleHold

Part of what you said it true. But think about the double your talking about with DDR2. Internal clock speed of 133/external of 266. There is your double. You dont double it from the 266 of the external. DDR only means you get two data transfers on each clock cycle, it does not increase the bus speed. So 1:1 with a quad pumped FSB 266/1066 is DDR2 533. We are talking about bus speed not transfer rates.


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## gamerman4

but to run your cpu in optimal sync with your RAM, you would want your CPU in sync with the transfer speed, not just the base clock which is why a Q6600 that has a 1066mhz FSB is best paired with DDR2-1066 and not DDR2-533.


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## tyttebøvs

Look at it this way: if the (double pumped) bus between the memory controller and ram is running at 266 (533) Mhz, how in earth will you transfer data from a ram module running at 533 (1024) Mhz?

Answer: You can't.

All the DDRx modules differ internally, but their connection to the outside world (the double pumped bus) is the same, and so is the calculations.

If you connect a raid controller to your computer, and build an advanced setup, will the OS address this any different than it does a normal drive? No.

If you connect a keyboard to a computer across the world, through an ip-based kvm switch, will the computer care? No.

Will your graphics care what type of display device you connect to its vga port? No.

The internals doesn't matter.


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## gamerman4

tyttebøvs said:


> Look at it this way: if the (double pumped) bus between the memory controller and ram is running at 266 (533) Mhz, how in earth will you transfer data from a ram module running at 533 (1024) Mhz?



because the 533mhz bus is transferring data twice as fast as it was in the original DDR spec.

The base internal clocks have not changed between DDR and DDR2 (except with the addition of a higher 266mhz clock) the only difference is that the bus is transferring twice as fast as before. DDR2-800 and DDR-400 have the same internal clock and when Intel used DDR, the cpus were still quad pumped and the ram was still double pumped and you still needed DDR-400 for optimal performance even though the FSB and bus (in DDR the bus and internal clock are the same) were both running at 200mhz.


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## tyttebøvs

The bus between memory controller and ram transfers data twich per cycle. This goes for DDR1, DDR2 and DDR3. How fast this bus can run increases with each generation. That is it.

It is not relevant in this context how the internals of the module works, and how it achieves this goal.


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## gamerman4

tyttebøvs said:


> The bus between memory controller and ram transfers data twich per cycle. This goes for DDR1, DDR2 and DDR3. How fast this bus can run increases with each generation. That is it.
> 
> It is not relevant in this context how the internals of the module works, and how it achieves this goal.



This was my initial statement



> when you see DDR2-800 you divide the "800" by 4 to get the base clock speed. This helps when overclocking because it is best to run your RAM at the same base clock as your CPU FSB.



this is what was contested and it is true, DDR2-800 runs at an internal clock of 200mhz, a statement i followed by saying it helps because that it is the same as your FSB in a 1:1 ratio. I never said RAM was quad pumped but that still doesn't take away the fact that it is best to run your CPU FSB as fast as your RAM can transfer data which just happens to be 4x as fast as its internal clock (mts can roughly equate to mhz since both are a cycle-per-second measurement).


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## StrangleHold

tyttebøvs said:


> The confusion might lie in the fact that the internal (chip) speed of DDR2 is half the speed of the external bus. So to get that, you divide by 4. But since it is all internal, it is rather irrlevant in these calculations.


 
This is the answer.


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## gamerman4

StrangleHold said:


> This is the answer.



and thats what i keep trying to say, but i wanted to argue that it is not irrelevant in the context I was using it in, internals do matter when overclocking.


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## StrangleHold

I think we are just butting heads on the difference between the internal and external speed of the memory in reference to the FSB and the amount of data being transferred. Good conversation though


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## gamerman4

StrangleHold said:


> I think we are just butting heads on the difference between the internal and external speed of the memory in reference to the FSB and the amount of data be transferred.



So I think we can agree that:

for DDR2 the internal speed is half of the double-pumped bus speed (obviously)
also the data transfer rate is twice the bus speed (the whole reason behind DDR2)
so in effect the transfer speed is 4x the internal memory clock and it is just a coincidence that Intel CPUs are quad-pumped so it is easy to match it with the data transfer speed of DDR2.

To elaborate on this, in the Pentium and Athlon days, DDR was standard
the internal clock = bus speed but thanks to the double-pumping, the data transfer rate was twice the internal clock

Athlon 64 cpus were 200mhz FSB and double-pumped = 400mhz
Pentium 4s (the older ones) were 100mhz FSB and quad-pumped = 400mhz
this was why DDR-400 was standard because it is best to sync CPU with the data rate, not the bus speed, BUT to get the data rate, it bases itself off of the internal clock, which is what you change in RAM when you overclock the FSB of the CPU.

This has to be the best pure technical discussion on CF we have had in a long time that hasn't involved fanboyism, flaming, or idiocy.


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## tyttebøvs

Sorry, but we cannot agree. You are stuck in the internal speed and that it has any relevance to this subject. It has not. DDR2 is no different in DDR in this matter. It it just able to run faster


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## StrangleHold

The Athlon/XP would follow that, but not the Athlon 64 (doesnt use the FSB) But thats true about comparing the data transfer vs. bus speed. But thats using the internal.


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## gamerman4

so the internal me clock has no bearing on bus clock at all? How is that possible when, for the bus clock to even have a purpose (or even exist) there has to be a mem clock?

The Athlon 64 may not have had a traditional FSB but its integrated memory controller did the same thing.


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## TrainTrackHack

> I am pretty sure overclocking relies on the internal memory clock as its base.


That is incorrect. All memory clockspeeds are based on the bus speed; the internal memory clock is sort of "behind the scenes" stuff and irrelevant.



> but to run your cpu in optimal sync with your RAM, you would want your CPU in sync with the transfer speed, not just the base clock which is why a Q6600 that has a 1066mhz FSB is best paired with DDR2-1066 and not DDR2-533.


THis is incorrect too. Remember the wiki article I quoted:



> Example: A Core 2 Duo E6600 processor is listed as 2.4 GHz *with a 1066 MHz FSB. *The FSB is known to be quad-pumped, so its true frequency is 266 MHz. Therefore, the CPU multiplier is 9×. The DDR2 RAM that it is compatible with is known to be double-pumped, *so to run the system synchronously (see Front side bus) the type of RAM that is appropriate is double 266 MHz, or DDR2-533*.





> so the internal me clock has no bearing on bus clock at all? How is that possible when, for the bus clock to even have a purpose (or even exist) there has to be a mem clock?


DDR2-800 runs at _effective_ clockspeed of 800MTs (i.e. it performs 800 million transfers per second, or two per clock since it's DDR), external or bus speed of 400MHz (this is what should be matched with the FSB, and also what we usually consider the true memory clockspeed), and internal clockspeed of 200MHz (this is directly tied to the bus speed, and nothing's actually based on this clock, making it irrelevant in this way - it's just simply not used).



> for DDR2 the internal speed is half of the double-pumped bus speed (obviously)
> also the data transfer rate is twice the bus speed (the whole reason behind DDR2)
> so in effect the transfer speed is 4x the internal memory clock and it is just a coincidence that Intel CPUs are quad-pumped so it is easy to match it with the data transfer speed of DDR2.


The internal speed is half of the _true_ clockspeed, so, again, the internal clock of DDR2-800 is 200MHz, not 400MHz. When using 1:1 divider, the external (bus) speed is the same as FSB, so the internal clockspeed is half of the FSB.


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## gamerman4

Heh, I just realized that about 45 mins ago when I was driving down the road. I was thinking about the old P4s vs the Athlon and how their FSBs were different and stuff, lol. I guess I was thinking about it too much and when I got on the road it let me clear my head. anyways, I was thinking that the FSB was connected to the mem clock but I realised the FSB is connected to the mem bus. What I had mixed up was that I was thinking the mem clock was double pumped but I realised it was the mem bus was double pumped and it became clear. I HAVE SEEN THE LIGHT!!!!! 
The main reason I was confused is that my BIOS has a multiplier of 4 but that's just the bus speed so if i had the multiplier at 4 with DDR2-800 it would actually be running at DDR2-1600 when I originally thought that it ran at DDR2-800, lol.


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## TechShark

I forgot to mention, I have windows Xp Pro, 32 bit, Will it be worth bumping my system up to 4gb? will it still use all 4gb? ive heard it only recognized 3gb.


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## 2048Megabytes

TechShark said:


> I forgot to mention, I have windows Xp Pro, 32 bit, Will it be worth bumping my system up to 4gb? will it still use all 4gb? ive heard it only recognized 3gb.



If you are at 2 gigabytes (2048 megabytes) of memory that is likely plenty if you are using the Windows XP Operating System.  What programs are you using with Windows XP and how much RAM do you currently have?

Edit:  Windows XP 32-bit will only utilize about 3.25 to 3.5 gigabytes of RAM out of 4 gigabytes (at least that is the information I have read).


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## TechShark

I understand Windows xp 32bit will only utilize around 3.25gb. But other than that, lets say a program that is really high demanding( this is hypothetically speaking) and needed a lot of ram. would this "program" be able to utilize 4gb, even though xp cant utilize it all.


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## Cromewell

No. Programs access RAM indirectly, they go through Windows (or whatever OS you happen to be running). So anything the OS cannot use the program running on it cannot see.


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## TechShark

So then, I should just stick with my 3gb, Since i dunno how much .25ghz will actually make a difference


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## Cromewell

It's your call but 4GB probably isn't much more than 3GB and then if you ever upgrade to a 64bit OS you will have all 4GB available.


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