# 1x16 vs 2x8 RAM



## TheNamelessPoet

Is there a benefit to a computer having 1x16gb stick of ram vs 2x8gb sticks?  Lets assume for this scenario that the RAM itself is the same. 
Corsair Vengeance LPX RAM DDR4-3000 for example.


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## Darren

TheNamelessPoet said:


> Is there a benefit to a computer having 1x16gb stick of ram vs 2x8gb sticks?  Lets assume for this scenario that the RAM itself is the same.
> Corsair Vengeance LPX RAM DDR4-3000 for example.


Yup. Dual channel increases memory bandwidth and you need dual sticks to achieve it.


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## TheNamelessPoet

Wow, fantastic quick video I like it  TY!!!

I have an _Asus Z97-Pro a_nd on PCPartpicker it has a 4x4GB Corsair Vengeance RAM kit.  That combined with the fact that it has 4 RAM slots (2 sets of 2 Gray/Black) means that it has 2 DUAL channels correct?  I currently have 3 4GB sticks in it that I am SURE none of them are a kit.


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## Shlouski

Darren said:


> Yup. Dual channel increases memory bandwidth and you need dual sticks to achieve it.



Darren, I went from 1x16gb to 2x16gb on my 8700k build and performance was more or less the same, even in cpu benching software, does dual channel make much of a difference on the AMD side?

CPUZ bench:

1x16gb:

Single - 586
Multi - 4503

2x16bg:

Single - 594
Multi- 4596

I'm a ram whore, so I always go with the single larger chip, so I have more room to upgrade in the future .


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## Darren

Shlouski said:


> Darren, I went from 1x16gb to 2x16gb on my 8700k build and performance was more or less the same, even in cpu benching software, does dual channel make much of a difference on the AMD side?
> 
> CPUZ bench:
> 
> 1x16gb:
> 
> Single - 586
> Multi - 4503
> 
> 2x16bg:
> 
> Single - 594
> Multi- 4596
> 
> I'm a ram whore, so I always go with the single larger chip, so I have more room to upgrade in the future .



I've never compared it without personally but I do know that Ryzen's architecture relies heavily on RAM speed so wouldn't surprise me if it're more noticeable on Ryzen platforms. Will it make a night and day difference (for any platform)? Probably not but it's always going to be faster (even if only a little). I imagine it's one of those things where most of the time it wouldn't have a tangible effect but when you saturate that bandwidth you'd notice it.

Do you ever see yourself needing a whole 64GB on your current platform? If not that then getting 1x16GB vs 2x8GB isn't that practical. Kits are frequently cheaper than a 1 off larger stick too.


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## TheNamelessPoet

So given this new knowledge (and ignoring color)...
It sounds like there is a benefit (albeit possibly very very minor) to getting 2x8gb for my computer.

Now expanding on that... I have 2 dual channels on my motherboard.  Does it make sense to buy a 2x8 OR, 4x4gb?   For example (aside from the $5 savings):
G.Skill - Ares Series 16GB (4 x 4GB) DDR3-2133 Memory
vs
G.Skill - Ares Series 16GB (2 x 8GB) DDR3-2133 Memory

Now I know the 4 do not work together because it is not a quad channel motherboard, HOWEVER is there any benefit to having both dual channels utilized?
If there is (even if it is tiny like SHLOUSKI pointed out it may well be) a benefit to using BOTH DUAL channels, does it make a difference if the ram is a 4x4gb kit that would work for a quad channel "kit"?

Also I notice the CAS Latency is 10 on the 4x4 and 11 on the 2x8.  Am I right in assuming a lower CAS number is better?


I am not sure if I am going to upgrade my RAM even this year (wife may kill me lol), but I am trying to learn as much as I can so that when I DO upgrade some day
I will at LEAST go up to DDR4 if not 5 when it comes out.  I know ill need a new processor and a new mobo, so I might as well understand RAM too


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## Shlouski

Darren said:


> Do you ever see yourself needing a whole 64GB on your current platform?



Sometimes I use ramdisk, less now as programs are getting so big and because of NVME raid its not really needed, but often I see around 80% ram usage with my 32gb.


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## johnb35

TheNamelessPoet said:


> Also I notice the CAS Latency is 10 on the 4x4 and 11 on the 2x8. Am I right in assuming a lower CAS number is better?


Yes


TheNamelessPoet said:


> Does it make sense to buy a 2x8 OR, 4x4gb?


2x8

2133mhz is pretty slow ram only a few boards actually support that as the fastest speed.  At this point if upgrading ram then get the fastest you can afford and what the board will support.


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## Shlouski

In most programs you won't see much (if any) real life difference between the fastest and the slowest ram, if you want faster ram then simply increase its speed and up its latency, you especially won't see any difference in gaming using a dedicated GPU. I have over the years realized a lot of ram is the same stuff or very close, clocked and timed differently, so different prices can be charge. I have collected a lot of memory modules over the years and for example I have 3 different modules of corsair vengeance ddr3, 1600mhz CL9, 2133mhz CL10 and 2400mhz CL11, each one of these modules can run at 2400mhz CL11 stable at stock voltage, my i7 3770k build still runs corsair vengeance ddr3 1600mhz CL9 @ 2400mhz CL11 and its 6 years old now and still stable. My new i7 8700k build has 32gb of crucial 2133mhz CL15, I bought it because it was the cheapest memory I could buy and I run it stable at 3000mhz CL17, which was just a guess setting I made when I first assembled the PC, it may run even faster at CL17 or its possible I could even lower the latencies, but I can't be bothered wasting the time for such miniscule improvements.


Here are the two faster modules up from my ram, which of course are more expensive:
http://www.crucial.com/usa/en/ct16g4dfd824a          2400mhz @ CL17
http://www.crucial.com/usa/en/ct16g4dfd8266          2666mhz @ CL19

My ram isn't just capable of these speeds and latencies, it surpasses them. Now sure this is not as fast as a lot of the memory out there, but it shows the relationship between latencies and speeds, take these ram modules for example:

https://www.amazon.co.uk/Corsair-CM...ir,p_n_feature_keywords_browse-bin:2841372031

https://www.amazon.co.uk/Corsair-CM...ir,p_n_feature_keywords_browse-bin:2841372031

These are most likely identical modules, one programed to run at 2400mhz CL14 and the other at 3200 CL16, but of course you will pay more for the 3200mhz CL16 modules or you could just buy the cheaper 2400mhz CL14 modules and run them at 3200mhz CL16. This is just one example, but I've been able to do this with almost every module I've come into contact with in the last 15+ years.


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## Darren

RAM speed is definitely noticeable on Ryzen platforms. I went from 2133MHz to 2933 and it was definitely noticeable.


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## Shlouski

Darren said:


> RAM speed is definitely noticeable on Ryzen platforms. I went from 2133MHz to 2933 and it was definitely noticeable.



I have a Ryzen 2400g in a media PC I built for 4k, I overclocked the ram from 2133mhz to 3000mhz so I could get the best out of its APU, which made a big difference of course, but CAS latencies seemed to have little to no impact. What sort of improvements did you see and do you know how much the latencies impacted on performance? If CAS latencies make very little impact then it may make sense to buy cheaper slower ram and just increase frequencies and latency.

Memory frequency have always been getting fast, but it has been at the cost of latency, I remember having some fast DDR2 Kingston HyperX 800mhz running at CAS4, now I see fast DDR4 running at 4 times the frequencies, but they are also running at 4 times the latency, its clear that frequency is the larger factor when it comes to performance.


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## Cromewell

Shlouski said:


> If CAS latencies make very little impact then it may make sense to buy cheaper slower ram and just increase frequencies and latency.


If you can increase the frequency enough, CAS hits are not noticeable because the higher frequency means it takes less time per clock tick. There is a section in RAM 101 about latencies in real time, it was added back when DDR3 was new, but the math still applies. It's at the end here: https://www.computerforum.com/threads/ram-101.11096/#post-87687


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## Shlouski

Cromewell said:


> If you can increase the frequency enough, CAS hits are not noticeable because the higher frequency means it takes less time per clock tick. There is a section in RAM 101 about latencies in real time, it was added back when DDR3 was new, but the math still applies. It's at the end here: https://www.computerforum.com/threads/ram-101.11096/#post-87687



Thx, I will take a look.


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## Intel_man

Cromewell said:


> If you can increase the frequency enough, CAS hits are not noticeable because the higher frequency means it takes less time per clock tick. There is a section in RAM 101 about latencies in real time, it was added back when DDR3 was new, but the math still applies. It's at the end here: https://www.computerforum.com/threads/ram-101.11096/#post-87687


Gamersnexus also has an indepth video on ram and what each component does. There's only part 1 so far, but it is fairly technical for those interested.


https://www.gamersnexus.net/guides/3333-memory-timings-defined-cas-latency-trcd-trp-tras


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