Prime95 - valid test?

I'm running my XP2500+ at 200x11 (stock vcore). It sails through Hot CPU, Sandra's burn-in, Memtest, and PCMark2002. However, if I try to run Prime95, the machine freezes after about 5 minutes. I've encountered no problems with any of my apps in this config, and playing Unreal Tournament for several hours straight posed no difficulties either. Of course, it bugs me to no end that it can't get past Prime95, even though I'm not entirely sure how applicable it may be, given the results I'm seeing with other stability tests. Has anyone else come across the same problem with Prime95, and did you find that eventually the stability of your rig was compromised, even though other stability tests indicated otherwise?

Your computer freezed??? or did prime 95 just give you an error? If your computer freezed then I dont know, if you are on dialup and you used resume for some reason prime 95 could be corrupt. Or memory could be bad or set too high of timings.

GlitchOfDoom said:

Your computer freezed??? or did prime 95 just give you an error?

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Thanks for the reply. No errors; the machine freezes after a few minutes in Prime at 200x11, but runs 170x12 and at 205x9.5 with absolutely no problems. As I mentioned, it runs 200x11 with Sandra, Hot CPU, etc, but for whatever reason doesn't want to work with Prime.

If your computer freezed then I dont know, if you are on dialup and you used resume for some reason prime 95 could be corrupt. Or memory could be bad or set too high of timings.

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I'm using 2x256 Corsair XMS PC3200, and Memtest shows no errors after 8 hours. I've relaxed its timing, and that didn't make any difference with Prime. Perhaps there's something I didn't do correctly. When I installed Prime, I opted not to run the tests online. Could this be causing the problem I'm having? It doesn't really seem like it would, but stranger things have happened.

Yes if you're just using Prime95 for stress testing you don't want to join GIMPS.

What version of Prime are you running? v23.6 is the latest and offers some new stability test options. Maybe you'll see different results from each of Prime's different testing modes, which could help you pinpoint the problem.

NookieN said:

What version of Prime are you running? v23.6 is the latest and offers some new stability test options.

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Indeed, I was using an older version. I downloaded and installed v23.6 and things are going much better; thanks for the tip! It's been running at 190x11 for a few hours now with no errors. I tried it at 200x11 and 195x11 and the thing froze every time. Raising vcore only made matters worse, making the machine freeze even sooner. Perhaps my logic is a bit off, but this makes me think the CPU is too hot. Motherboard Monitor shows the temp as 41 under full load, as does Sandra and bios (I'm using a MSI K7N2 Delta-L mobo and a Thermalright SK-7). It is said that MSI's bios intentionally show lower temps, but the HS feels relatively cool to the touch under full load, so I dunno...

ll see different results from each of Prime's different testing modes, which could help you pinpoint the problem.

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Great idea! I'm on it

What do you think about my temps? I mean, is it possible that the CPU is overheating, even though I'm getting reasonable-looking readings and the HS doesn't feel particularly hot? It's not cold by any stretch of the imagination, but it's hardly glowing either. I made *very* sure that it's installed correctly and applied AS3 between it and the processor. My case is very well ventilated, but to rule-out that variable, I've been using it without its side panels attached. My room is at 25-30 degrees max.

I guess I'd feel better about this if Prime was showing errors, but the freezing has me scratching my head, especially since the machine can run other tests with no problems.

Look into your Powersupply. when you raise the CPU speed it draws more power and if the PSU can't keep up the Vcore starts bounceing around instead of hanging out in a fairly narrow band. CPUs rather dislike such voltage fluctuations.

Use MBM5 to track your vcore while under load and see how much it varies. Granted it isn't spot on with it's measurements but it will expose the trend never the less.

i can't run prime either. THe latest version of prime is no dice as well. At stock speeds it'll even give me errors. I don't know what's the deal. I can run Sandra burn in, f@h, and s@h for hours on end. Not to mention bench in 3dm03 and 01. I don't understand what's the issue. My proc is @ 100% load right now and mbm shows my vcor @ 1.76v.

AKULA said:

Look into your Powersupply. when you raise the CPU speed it draws more power and if the PSU can't keep up the Vcore starts bounceing around instead of hanging out in a fairly narrow band. CPUs rather dislike such voltage fluctuations.

Use MBM5 to track your vcore while under load and see how much it varies. Granted it isn't spot on with it's measurements but it will expose the trend never the less.

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It's interesting you say that, as I've been looking at the power rather closely. I've noticed no variance under load. I'm using a Chieftec 420 watt, which is a rebadged Enlight EN-8420934. To tell ya the truth, I almost wish the PSU performed worse than it does, because that would explain the problem I'm having and provide an easy fix.

chowdy - if it's givin you errors even at stock speeds, then something's definitely wrong, but i don't know what

Try your RAM at CAS 2, this sounds stupid, but I've been hearing of a few tbreds and bartons that have wierd errors at slower settings.

what mobo are you using?

try 12.5x 176 FSB = 2200. Maybe it's your FSB that's causing problems??

RoadWarrior said:

Try your RAM at CAS 2, this sounds stupid, but I've been hearing of a few tbreds and bartons that have wierd errors at slower settings.

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I tried it, thanks. Setting the timing at 2-2-2-11 yelled the best results yet at 200x11. Prime locked-up after about 1/2 hour instead of the usual 2-5 minutes. I still can't figure out why HotCPU, Memtest and Sandra's burn-in can run seemingly forever, but Prime locks-up the machine. Similarly, all apps run perfectly, too.

01_VTEC SE said:

what mobo are you using?

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It's a MSI K7N2 Delta-L. I've noticed that other folks with the same mobo are also having problems with Prime, so perhaps it's some weird interaction with the mobo that's responsible. I'd really like to get to the bottom of this.

Still looks to be a volt problem though, even with the cpu at stock.
I'd opt out the PSU and grab an antec 400 watter or something of the sort. I had the same problem with my T-Bred. Everything els ran perfectly, just Prime95 would hang after 5-10 minutes. Then i swapped the PSU and POW.......no more problems.

blkgti said:

I tried it, thanks. Setting the timing at 2-2-2-11 yelled the best results yet at 200x11. Prime locked-up after about 1/2 hour instead of the usual 2-5 minutes. I still can't figure out why HotCPU, Memtest and Sandra's burn-in can run seemingly forever, but Prime locks-up the machine. Similarly, all apps run perfectly, too.

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Prime95 puts a loooot of stress on your CPU and memory, I think
more than what any other application possibly does
For sure it's way more stressful than Sandra, 3dmark, etc...
they don't even come close to this thing...

for me 1 hour Prime w/ no error means a highly stable machine
if I can repeat the experiment a few times of course.
more than 1 hour is ice on the cake...some people are not
satisfied until they run P95 for a couple of days!

I agree with the power problem people. I have had similar problems with my dual athlon board. I think that the voltage regulators on my board weren't too good....Anyway, it would run at reduced speed and lowered voltage, but not at stock.
The reson people like prime 95 as a hardware test is that it is pretty much OS independent. The code for it is almost all ASM, and so it works on the hardware level stressing the cpu to the max....Anyway, I'd look into your PSU first and then the mainboard....

PS. I often couldn't see the voltage dop that would make things freeze.

TLhead said:

I agree with the power problem people. I have had similar problems with my dual athlon board. I think that the voltage regulators on my board weren't too good....Anyway, it would run at reduced speed and lowered voltage, but not at stock.
The reson people like prime 95 as a hardware test is that it is pretty much OS independent. The code for it is almost all ASM, and so it works on the hardware level stressing the cpu to the max....Anyway, I'd look into your PSU first and then the mainboard....

PS. I often couldn't see the voltage dop that would make things freeze.

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if the onboard regulators are not too good, do u think replacing the PSU would help??

I am having pretty much the same problem with Prime95
and I do suspect a power problem somewhere but my voltage
readings are quite stable...

You can tell if it is the PSU by monitoring the voltages in MBM or even better with a voltmeter. If all your voltages are stable except the vcore and or vdimm then I would say it is likely a board problem, but if you see fluctuations in the 5, 12, or 3.3V lines the PSU would be the culprit.

To answer your question more directly, if the MB regulators are the problem, it's time for an RMA. MSI was pretty easy to deal with when I got mine. I hope this info helped and you can get it working! It's soooo frustrating to get a nice new part and it doesn't work as advertised.

TLH

TLhead said:

You can tell if it is the PSU by monitoring the voltages in MBM or even better with a voltmeter. If all your voltages are stable except the vcore and or vdimm then I would say it is likely a board problem, but if you see fluctuations in the 5, 12, or 3.3V lines the PSU would be the culprit.

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I ran HotCPU and kept a very close eye on the voltages at full load with MIM5. There was a slight fluctuation in vcore - 1.63-1.66 - but all other voltages were totally stable. The variance in vcore amounts to ~2%. That seems like it's within spec, or is this something I should be concerned about?

First up, Welcome to the forums, blkgti!

Second, if you are not bothered about one stability test, do not worry - My machine will only tolerate about 30 minutes of Prime95 before giving up, but for what I want (Gaming, Internet, Multimedia) the system is rock stable, even when running it at 100% load with Folding@Home (If you don't know what this is, look for the Folding Team forum, located on these message boards).

Admittedly some people will never sleep until their computer will run Prime95 flawlessly for days on end, but I'm not one of those people