Prime95 rounding errors

Anyone got any ideas? I have built a new rig (specs below) and its been running fine on standard spec. I recenlty started to overclock but hit a brick wall at >200fsb. I have locked multi so no chance of mucking about with that. System is running fine...no lock ups or crashes, but one thing is *****ng me off...I can't get prime95 to run for more than 40 secs !!!

I get:-

FATAL ERROR: rounding was 0.5 expected less than 0.4 on the blend test and a similar failure on large fft test. the small fft is ok.

memtest passes with flying colours as does sis sandra, but i read that prime is the holy test !

I'm running stock volts at the mo, but have messed with and makes no difference.

Temps are 41/23 as i type. My motherboard is a V2.0 nf7-s and is due a bios upgrade, but i'm fairly sure that wont cure it.

halo, splinter cell, MOH, play without any glitches.


any ideas, or is this a bs program.

It ain't BS. Basically it means you've errors in arithmetic due to memory or cpu problems. Prime is stressing your computational compoents. The OS and other apps (like games for example) are obviously smart enough to guard against these types of porblems some times. Arithmetic not important to you then you can disregard but it does indicate things aren't stable.

Errors mean you have instability. It might surface when you do a 5 hour gaming binge, your computer heats up, and hard crashes. Prime stresses your CPU and RAM more than games, so that is why it is giving errors. Try a little more voltage. That should fix it. A bios flash to D20 or D10 might help too.

I gave up on prime the only way I can get it to run longer than 2 minutes is at stock settings...I'm in the same boat...no crashes I can run sandra for 24 hours memtest for 12 hours no errors...so I uninstalled prime and vow never to use it again

ok well now I screwed with some more things and reinstalled prime and its finally running its been running almost a hour now I just changed my mem timings from 2.2.2.7 to 2.2.3.7 and its prime stable...

World Cup you're prime95 stable at 200?

a while ago i got some corsair xms pc3200 and it was 9 hours prime95 stable, bumped it up 1 notch on my board so the freq was at 202 and prime95 would crash immidiatly.... at any voltage too btw...

it's very posible you got a crappy overclocker just like the one i had...

Damn, thats pretty tight to spec on your memory there. 202 and errors. Have you tried upping the vdimm?

My system has been tested to stability with nothing BUT Prime95. It just seemed to me as though it always corresponded with other errors in the system. Sure a large percentage of things will run without a problem, but a certain type of error would make NFS UG dissapear on me in the middle of a race.

If you're only running the default stress test, I suggest you run the one with Small FTT's to see were your CPU's limit really is. Because at lower speeds than I am right now my Prime95 wasn't failing unless I was running the default test that crunches up the memory, I knew my processor was capable of more... and now look, a few CAS latencies increased later and some more Prime95 stress testing, and I've found out my computer is capable of a lot more than I ever thought it would be.

Remember, sometimes when Prime95 crashes out in the default test, that's often only a memory problem such as mine was. Check the Small FTT test and if it's doing good after the first 4 runs you're good to go... if not, increase the voltage, if that doesn't help and heat gets too high, get better cooling (My SmartFan II decreases temps by 20C compared to the 92mm case fan I had on before, and lets the CPU get a much better OC)

Cheers Guys,

been messing with the memory timings...now at 2.5,3,3,7, from 2,3,3,6 and it's better, but not perfect..passes all but the last torture test, but is running for 4-5mins now. I also upped the vcore to 1.75 & vcc to 2.75 . I'm now trying to work out whats the restricting factor so have put the board voltages back to default to see what i get.

if it is the memory timings, can anybody tell me whats typical for these corsair matched (twinx) xms3200pros ? i was led to believe that these were a good match for a system of my spec ?

Sorry login211, forgot to mention...not stable at 200 on prime95, but fine with every other prog.

Fleck said:

If you're only running the default stress test, I suggest you run the one with Small FTT's to see were your CPU's limit really is. Because at lower speeds than I am right now my Prime95 wasn't failing unless I was running the default test that crunches up the memory, I knew my processor was capable of more... and now look, a few CAS latencies increased later and some more Prime95 stress testing, and I've found out my computer is capable of a lot more than I ever thought it would be.

Click to expand...

ok so if I'm passing the small fft's and failing on the default 'blend' torture test then is it my memory thats causing the failure?

also anyone know if upping my chipset voltage would help anything?

dubtek said:

ok so if I'm passing the small fft's and failing on the default 'blend' torture test then is it my memory thats causing the failure?

Click to expand...

That's been my experience... I have tested it and found it to work.