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Prime95 priority matters?

post #1 of 22
Thread Starter 
i read on the msi forum that p95 priority should be set to 10 for stree testing.
http://forum.msi.com.tw/index.php?topic=33850.0
quite an old post i know but maybe it still applies?

then i read some posts on XS suggesting the opposite.
http://www.xtremesystems.org/forums/...45&postcount=6
http://www.xtremesystems.org/FORUMS/...71&postcount=3

so now i'm confused especially i can't find the official prime95 FAQ the XS post quoted from.

i finished a 25hour 50minute prime95 run with the following setting: Blend, RAM usage=2000mb, Priority Lv=1. I then rebooted and let the system idle for around 20min then run it again with: Blend, 1845mb, Pri.Lv.=10, and it failed with rounding error in core 2 after 11 minutes.

I had Cpu-z and core-temp open alongside p95 in the 25h run but used real-temp in the second run since core-temp freezes when p95 priority is 10. Screensaver and superfetch were disabled.

so is my OC unstable?
does the priority setting make a difference?
should i run p95 in Safe Mode to make sure nothing in background steals cpu cycles?
post #2 of 22
Hmm, this is extremely interesting, but I will say that this is the first time that I have personally ever seen anyone here on Overclock.net bring this up (I have never known about it).

However, it does say that screensavers run at a priority of 4, and most applications run between 7-9. I've also seen people say that they can get any stress test to last longer by purposely stealing CPU cycles away by running Firefox, their e-mail client, or some other light program (it was said that it didn't take much). So with that in mind, I would be inclined to believe that using a Priority of 10 is the better option.

But, I can't deny that I've never seen this brought up before, so I don't know.

Edit: I will add this: what too many people don't know is that the computer should be left alone while it's stress testing. Way too many people insist on trying to use their system while a stress test is running, and then they come back to OCN 2 months later saying that they're having problems with instability. This is because their system wasn't really stable to begin with because they rendered those stress tests useless due to using the computer while they were running!
Edited by TwoCables - 6/5/10 at 2:58am
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post #3 of 22
Your OC is unstable.

Essentially, the higher the priority, the more the calculations the stress test is doing would be prioritized over what ever else is going on. If you've got it set to a low priority, even when you're not using the PC, background apps can be using CPU cycles, and they will get priority, meaning the chip is not fully tested.
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post #4 of 22
Thread Starter 
Thanks for the replies. I never use my computer when it's stress testing or benching etc. screensaver was disabled. i also tried to disable as many system services as i could. but i left some 3rd-party drivers running like the G15 LCD driver etc.

I'm running the priority 10 test again in safe mode and so far there's no error and it's been 20 min! (no change in voltages etc , only differences are Safe mode and no monitoring program like real-temp in background)

@TwoCables ,
i noticed that we have similar specs (cpu and ram at least), can you please tell me some of your voltage settings?

My settings:

cpu freq: 4 ghz (445x9)

vcore: VID=1.25v, 1.34375v (bios), 1.32v (idle in win7), 1.288v (100% load in IBT/LinX)

PLL: @default 1.5v

VTT: 1.2v (up from default 1.1v)

NB: 1.16v (up from default 1.1v)

LLC: off

Asus clock twister(dram drive strength or something): lighter

cpu margin enhancement: performance

RAM: Mushkin 996533(2gb kit) and 996533B(2gb kit). The older 996533 kit is discontinued and 996533B is the replacement. The specs on Mushkin's site are the same. I'm runing @4-4-4-11 with tweaked sub-timings @ 2.1v @1:1 890mhz @ Performance Level 9

I'm particularly interested in your vcore, nb, vtt voltages and if your ram sub-timings are at auto setting or manually set? coz i want to know what voltage to increase if p95 fails again in safe mode.

some of my earlier p95 testing results:

results below are all run @ the above voltage settings except NB voltage. P95 test is Blend @2000mb ram usage @ priority 1

nb@1.1v(default): calculation error in core1 after 4h 8m

nb@1.12v: calculation error in core2 after 11h 39m

nb@1.14v: calculation error in core2 after 11h 46m

nb@1.16v: PASSED 25h 50m @63C but failed Blend @1845mb @priority 10
Edited by AE86@10KRPM - 6/5/10 at 11:22am
post #5 of 22
Thread Starter 
furk!

looks like i was too happy too soon , p95 failed in safe mode after 57minutes.

looks like Hazzman was right about my OC being unstable.
post #6 of 22
Ugh, and this is why I don't use Prime.

Try OCCT - I've had much better results myself. If you can do an hour or 2 of OCCT, I'd consider it stable. OCCT tends to find things in the first 10 minutes that Prime can take hours to find.

http://www.ocbase.com/perestroika_en/index.php?Download
post #7 of 22
Quote:
Originally Posted by 9KRacing View Post
Ugh, and this is why I don't use Prime.

Try OCCT - I've had much better results myself. If you can do an hour or 2 of OCCT, I'd consider it stable. OCCT tends to find things in the first 10 minutes that Prime can take hours to find.

http://www.ocbase.com/perestroika_en/index.php?Download
Then perhaps OCCT is natively programmed to run at a much higher priority than just 1. I mean, OCCT's "Data Set' tests are identical to the three preset tests in Prime95.

Edit: I just looked, and this is correct. OCCT's priority is set to "Normal", but there are priorities both above and below it. Prime95's default is 1 which is the lowest.

In other words, changing the Priority in Prime95 to 7, 8, 9 or 10 makes it equal to or superior to OCCT.
Edited by TwoCables - 6/5/10 at 11:52am
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post #8 of 22
Thread Starter 
i thought OCCT was outdated? maybe i'll redownload and try it again.

did some more testing the whole day yesterday and it's been a,well, really "stressful" day (no pun intended ).

Since i went from 2gb(2slots) to 4gb(4 slots) , i kept upping the NB voltage until it reached 1.3v. 1.3v is the highest i'm willing to go and prime still failed with rounding error in core1 after 19h 13m.

Looks like i'll have to up vcore or vtt? i'm reluctant to up the vcore coz i found it to be stable with the current 1.288v[load]. hours of IBT/LinX.

I can understand if changing priority in prime95 makes a difference in the result but this much difference and headache? no.

urge to smash keyboard against head ... rising ...
post #9 of 22
OCCT is the way to go. Unless you enjoy waiting 24 hours for results.
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post #10 of 22
Quote:
Originally Posted by AE86@10KRPM View Post
i thought OCCT was outdated? maybe i'll redownload and try it again.
Thanks to this thread, we have discovered that OCCT uses a higher priority than Prime95. OCCT's default priority is "Normal", and has one higher than Normal, and two lower than Normal. This tells me that it's kinda like with Prime95's settings, except Prime95 allows a number to be selected from 1-10. Based on OCCT's default setting, I would venture to guess that "Normal" must be a priority of like 7-8, while Prime95's default is just 1 (remember, Prime95 says that a screensaver uses a priority of 4, and most applications use 7-9).

Therefore, this explains to me why some people say that OCCT is superior even though they could make OCCT and Prime95 perfectly identical by setting Prime95 to a priority of 10, OCCT to "High", and running the equivalent tests of Small FFTs/Small Data Set, Blend/Medium Data Set, In-place large FFTs/Large Data Set.

Quote:
Originally Posted by AE86@10KRPM View Post
did some more testing the whole day yesterday and it's been a,well, really "stressful" day (no pun intended ).

Since i went from 2gb(2slots) to 4gb(4 slots) , i kept upping the NB voltage until it reached 1.3v. 1.3v is the highest i'm willing to go and prime still failed with rounding error in core1 after 19h 13m.

Looks like i'll have to up vcore or vtt? i'm reluctant to up the vcore coz i found it to be stable with the current 1.288v[load]. hours of IBT/LinX.
IBT and LinX are identical in that they both use the same Linpack test. It's just that LinX has a superior GUI.

Quote:
Originally Posted by AE86@10KRPM View Post
I can understand if changing priority in prime95 makes a difference in the result but this much difference and headache? no.

urge to smash keyboard against head ... rising ...
Why do you consider it a headache? I mean, why not consider it a way to make your system even more stable?
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