Finding the bad component

[skisteven1]

I've got a whole bunch of newish dells deployed in an enterprise environment. They're P4-HT's with 2x512 ram, running XP Pro.

Lately, several of them have started having random reboots or bluescreens. In the process of trying to figure out what's wrong, I've done the following:

memtest86 for 24hrs+
upgraded bios
upgraded chipset drivers
replaced ram
rinse; repeat.

I have also been running 2x Prime95 on the failed machines, and come up with some interesting results. I'm hoping that some of the more experienced Prime95 / CPU people out there can help me pinpoint the problem.

On "good" machines, I can run 2x Prime95 instances in any test (small fft, large fft, or blend) for hours on end with no problem. On a "bad" machine, even after replacing the ram with known good ram, I cannot. Currently, I have a machien that will FAIL Prime95 after a few minutes when running "In-place large FFTs". It never fails small ffts, and occasionally will fail on blend -- but ALWAYS fails the Large FFTs test.

I'm not really sure what to make of this, so I'm hoping you might be able to help. None of the machiens are overclocked, and the BIOS is such that I couldn't change clock/voltage if I wanted.

I read somewhere that when a machine fails only on the "in-place large FFTs", that generally indicates a problem with the mobo / northbridge. Has anyone else heard this?

Any advice or help anyone can offer would be greatly appreciated. I've never heard of erroring only on 1 of the tests before -- have you?

Thanks!

 

[GuitarDaddy]

Large files generate the most heat and consume more energy. I would suspect power supply and/or poorly seated HSF.

In my experience with big box computers the PS is usually the weakest link. I would invest in a cheap PS tester, and specifically look for drooping numbers on the 12v. And use a temp monitoring program to help identify machines with poorly performing HSF's

 

[Assimilator1]

IIRC large FFTs strain the RAM & mbrd the most ,seeing as you've swapped the RAM it can't be that ,after you've tried GuitarDaddys suggestions then the mbrd would be the next candidate.