# 1 slow core on prime 95 q9550



## boonet

Hi

When i oc'd my cpu to about 3.865 ghz, i ran prime 95 and i noticed worker 2 (on physical core 1) was working like 10 times slower then the other ones. 

Is this maybe because windows vista tries to lock the working programs to 1 core when the others are fully used by prime ( in this case)? 

When i put the settings back to default, this was again the case but a lot much noticeable ( but this time on core nr 2 of 3), and it ran on a much lower temp then other 3. 

So does vista lock working programs who doesn't need much cpu to 1 core causing 1 worker on prime 95 to slow down, or is it because i have a bad cpu.

Thx boonet

specs

P5Q pro
q9550 @ 3.865
8 gigs dominator
750 w corsair psu
eah 4870X2 
some hdds
scythe mugen 2
antec 1200


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## Domain_Man

Hi Boonet, our setup is very similar..nice choice!  

Your gut instinct may well be correct, to prove it try running prime 95 on safe mode where your normal vista programs aren't running on the background and see the difference.


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## boonet

this evening i'll surely do that, afterwards i have another question, what are your settings to achieve 4 ghz and is it stable?  im now at 3.8 stable, but i cant get the 4 ghz large fft test stable... 
That bios u have, is it a newer version than the one on mine? I have marvell 1.1.00 or something like that. were can i download it, and how do i have to install it?

I cant imagine i finally found someone with almost identical rig as mine!!!! 


thx boonet


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## Motoxrdude

Yeah that sounds about right. Other programs are still running and need use a one core to do their thing, which would explain why prime95 is running slow on that one.


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## Domain_Man

Hi Boonet, I got to 4ghz by spending a lot of time tweaking my bios settings then running prime 95 for a minimum of 7 hours.

To get your q9550 to 4ghz, you may need a different setting completely, even if on the surface our rigs looks the same.

The first thing you need to check is what stepping version your q9550 is. There are 2 versions a C1 stepping and an E0 stepping, the 2nd one being the latest version and easier to get to 4ghz without too much trouble.

Run CPU-Z and on the first tab check under revision if it's E0 or C1

Also find your CPU's vid, download CORE TEMP and it will say under VID. 

To check your bios version, on CPUZ it will be under the mainboard TAB. You can download the 1406 bios from the Asus website.

What is your ram spec?


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## boonet

yeah i read this tutorial on how to overclock (http://www.ocforums.com/showthread.php?t=515316), im still trying to get it right, my stepping is C1, i know its not as good as E0 but i will try to get it to 4 ghz. Ram is 8 gigs of dominator at 1.066 ghz

my vid is 1.2250V, however i set my cpu voltage to 1.37500 in the bios. Is this the famous vdroop? 

Ill download the new bios because i have the 1306. 

Can you give me your bios settings for me to know were to start?

thx boonet


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## Domain_Man

Hi Boonet, that's a good guide. 

I think you're nearly there. I don't think it's the vdroop, it's more likely your voltage combination. Plus vdroop can be treated by enabling 'load line calibration' depending on how much voltage fluctuation you have, leaving it disabled isn't bad)

Try this setting for your setup:

CPU Ratio - 8.5
FSB Frequency - 471
FSB Strap - 333
PCI-E Frequency: 100
Dram Frequency - choose the lowest setting out of the 3 (for now)
Dram Timing Control: Manual
Try 5, 5, 15 and leave everything on auto

DRAM Static Read Control -Disabled
DRAM Read Training -Disabled
MEM OC Charger - Disabled
CPU Volt - 1.39 (start with this voltage for now..if unstable increase the voltage slowly)
CPU PLL - 1.5
FSB Termination Voltage 1.26
DRAM Voltage - 2.1
NB Voltage - 1.4
SB Voltage - 1.2
Load line Calibration - Disabled
CPU Spread Spectrum - Disabled
PCIE Spread Spectrum - Disabled
C1E - disabled
Max CPU ID Value Limit - Disabled 

Prime95 it for 2 hours initially and let me know your temps...


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## boonet

ok thx, isent the vcore to much? isnt it over the recommended of intel?
its for 24/7 use, (not always up, but i just want to be able to use this oc always, not needing to go back to other settings because i know i otherwise will fry my cpu in less then 2 years)

thx boonet


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## Domain_Man

http://download.intel.com/design/processor/datashts/318726.pdf

According to Intel, on page 19 of the link above, the absolute core voltage rating is 1.45v


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## boonet

uhu, but http://processorfinder.intel.com/details.aspx?sSpec=SLAWQ thats the vid.
but whats the diff between vid and vcore? i know my vid is still a little low but i dont know whats the difference. But im going to try your settings. 

Thx boonet


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## Domain_Man

Hi Boonet, don't worry
0.85V – 1.3625V is the average expected VID (voltage identifier digital) to pass through the chip on stock settings.


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## boonet

ok now i get it, so max vcore is 1.45. 
i updated to latest version of bios, tomorrow ill use youre settings...

thx alot friend...
boonet


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## Domain_Man

Nice one Boonet, glad to help!


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## boonet

hmmm, help me on this one: no matter what i do to the vcore, it prime still stops with 1 error after 2 secs or somthing, i enabled my load line callibration, otherwise my vcore went from 1.39 to 1.28 and stuff like that. Now my vcore in the bios is at 1.4125 somthing like that but i doesnt matter if i pick this vcore or 1.36875, it still crashes within 2 seconds. i already upped my nbvolt, sb volt, vtt volt.. (Oh yeah its always core 0 or 1 that crashes)... nothing helps? what should i do?

boonet


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## Domain_Man

Boonet, keep the other settings the same as before. Just change the vcore to 1.425 and cpu pll to 1.56 then prime it..

Also what are your load temps?


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## boonet

the more vcore i put trough the faster it gives an error? now its instantly when on vcore 1.425 and themps are 85-85-74-75 when in small ffts ( large won't last long enough to watch the temps :S). I put evrything like u did, only changed the vcore 

wtf is going on here?


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## Domain_Man

Temps are too high for cores 1 and 2, drop the vcore to 1.4 

Let's check your FSB overclock - drop the cpu multi to 8, so it's 471 x 8 then prime it


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## boonet

hmmm ok i think i misplaced my cooler... ill need to mabe lap it or somthing like that.
but ill lower the vcore and the fsb then see what happens..

thx


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## boonet

still error after 2 seconds
im going to try vcore of 1.36 and see what happens


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## boonet

this doesent help.... maybe a fault of ram??
whatever i do, it keeps crashing after a sec or two...??
temps: 68-68-61-60


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## Domain_Man

boonet, this is progress!

Lower the vcore to 1.375

Drop the FSB all the way to 400

Then prime it..

your ram could be your bottleneck as you thought but need we to prove it first...


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## boonet

i did the fsb drop, but i forgot lowering vcore... what i noticed during the quick 10 min run of prime was stability... i think this implements that it can get stable at this speed....

boonet


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## boonet

i think this also implements thar the fsb is the problem( maybe the ram indeed) because: small ffts show there is a good stability just for the core...( did this for 6 hours at 4 ghz vcore: 1.3625 and ws stable), and it shows the ability of getting stable with


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## boonet

large ffts with an fsb of 400...but how can the ram be the problem? its 1066mhz dominator! 

srry for the splitting of posts, im on my phone and i cant the more then 260 characters

boonet


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## Domain_Man

2 things to try...

1. Increase ram voltage to 2.2

2. Try taking 2 ram chips off at a time and prime it


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## boonet

1st doesnt work, second doesent work.. tried someone elses settings, this has the longest stabiltity on large ffts :
fsb 471
pcie frec 100
fsb strap to nb 333
dram freq 943 mhz
dram timing: 5-5-5-15
dram static read: dis
dram read trainging: dis
mem oc charger: enabled
ai clock twister: light
ai trans. booster: auto

cpu volt; 1.3825
cpu gtl: 0.65X
cpu pll; 1.52
fsb termination: 1.40
dram: 2.10-2.20 (doesnt matter )
nb volt: 1.40
sb volt: 1.30
pcie sata volt: 1.50

llc: enabled
cpu spread: dis
pcie spread: dis
cpu clock skew: 300ps
nb clock skew: 200ps
cpu margin enhancement: optimized

this all gives a minute without errors, instead of 2 secs...

i dont really think its the ram, but right now my instinct say it doesnt know, maybe fsb so ram ( but i dont know ectually)...

what should i do from now, i tried tweaking those settings, but this is the closest i can get to stabilty

boonet


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## Domain_Man

If it's not your ram then its possible that your northbridge is HOT with the FSB overclock. Unfortunately there's no temp sensor on the P5Q Pro northbridge, but if you google this you'll find how other P5Q Pro owners were able to tell if its overheating. If this is the case you will need a northbridge fan, similar to the OC guide you have read.

Here's one last setting to try, otherwise you'll have to settle for a lower oc for now. (NOTE USE THIS SETTING ONLY WITH THE LATEST P5Q BIOS)

cpu volt; 1.4
cpu gtl: AUTO
cpu pll; AUTO
fsb termination: AUTO
dram: 2.1
nb volt: AUTO
sb volt: AUTO
pcie sata volt: AUTO


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## boonet

ok ill try that, tomorrow ill search for the nb overheating thing. the northbridge is almost against my cpu cooler=mugen 2 because the cooler is that big, maybe this is the problem? maybe indeed it overheats.

Can't it be a problem of temps from the cores? its always core 0and 1 erroring, and those 2 get the hottest, sometimes even 8 degrees hotter... 
could this be the problem? maybe ill reseat my cooler, but i dont know if i will be able to do that with my dominator memory, but ill try in the weekend to get the temps even, maybe ill need to lap my cpu... I have the 1613 bios now i think

boonet


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## Domain_Man

Hi Boonet - remember you were having the same problem when you lowered the cpu multiplier but kept the FSB Overclocked. - This is your bottleneck

With regards to your northbridge chip, having a Northbridge fan on a P5Q Pro is always a good idea!

But - There is no doubt you have 2 cores overheating on a high overclock and that needs fixing, rather than lapping your cpu at this point (you can do this later if you wish, but it's easier to sell an unlapped cpu later on when you get bored with it) make sure you applied the correct amount of thermal grease and on the correct location of the cpu for a quad core as demonstrated below:

QUAD CORE GREASE 

Bonus points if you can do a neater job! 

And reseat your HS firmly.

I hope this helps!


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## boonet

what i understood form other forums ( http://forums.extremeoverclocking.com/showthread.php?t=310787 ) is that asus used the worst thermal grease ever... im going to reapply it , like on the faq included in the forum. afterwards im going to try to mount my second dominator fans on the nb hs... im just going to try that. i dont think im going to take the southbridge of... im going to remount my mugen 2 because right now it is on top of the the nb, im goint to make it point to another direction. maybe im going to lap it afterwards, but i dont know realy.. first going to remount it with the paste like on ur photo...
ill keep you in touch

thx


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## boonet

if anybody is still listening: I found somthing on internet about the cpu margin enhancement, apperantly someone had hit 4ghz with minimum volts. 
But hes cpu margin enhancement was on compatible, i did this with mine, and guess what, all problems were solved !!! im now running prime for 6 hours blend testing....

btw i remounted my hs, couldnt reapply the thermal paste to the nb cooler because of the stupid push in pins i couldn't get back out.... do you know how i can get them out???

temps are still 5 -10 degrees higher on load speeds at core 0,1 but i think its just because the weight or something like that... 

i did attach a 40 mm dominator fan to my nb, but i don't think that was the great problem, but now it runs cooler i suppose

I dont know if u knew about the cpu margin enhancement in the bios, but maybe iff u would set it to compatible, u could get even higher oc's or lower volts...

boonet


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## Domain_Man

Boonet, congratulations! This was all credit to you for persevering, a job well done. I'm going to the pub to celebrate!


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## boonet

nice, thanks, i still dont really know what the cpu margin enhancement means, do i have less performance when i put it on compatible, then when i would put it on performance.? i don't get what it does....

but now i can finally go tweaking for real, to get the best stable settings !!! im so happy

boonet


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## boonet

i have still a lot higher temps on first 2 cores then on last two, i noticed a diagonally touch with the ihs...

when i take it of next time ill post a pic, but the problem is it takes 3 hours or more to get evrything out, put it back in ....

boonet


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