> Could someone explain this "noisy" cache/RAM? That sounds like it may be
> the problem.
Since the cache on the PII's is built in, saying it's a cache problem might
as well be the same as calling it a CPU problem.
> More facts for you detectives out there:
>
> 1) This is a Dell Optiplex. All three models (slimline, desktop,
> midtower) exhibit this behavior.
I assume the video card is similarly close to the CPU in all those models?
> 2) I don't think heat is the problem. The problems start within 5-10
> seconds of starting prime and stop as soon as prime is halted.
Then we can say it's related with some certainty.
> 3) The on-board ATI graphics chip is about 2 cm away from the Slot1,
> directly underneath the CPU's big heat sink.
That's *way* too close, I would think.
> 4) The distributed.net client does not cause this behavior. My
> understanding is that it does not use either FPU or cache.
Since you don't see the problem normally, my gut instinct tells me it's
related to FPU activity.
The cache and integer bits of a PII are used with some regularity even if
the machine is just sitting there.
One good test would be to use any other program that uses the FPU alot and
see if the flicker shows up. Can anyone think of another program that
would? I suppose any benchmark that tests FLOPS should do the trick.
