Help! My computer shuts down semi-unexpectedly.

Question

Please somebody help! My computer shuts down semi-unexpectedly. I say 'semi' unexpectedly, cos, by now it seems an accident waiting to happen ONLY when I play a 3D game.
Now, whenever I play a 3D game there's a good chance the computer just shuts itself down, without ANY warning. Can be within 5 minutes, can be after an hour, it sometimes doesn't happen at all.
After this the computer will not start up at all, and the D-bracket tells me the processor is the culprit. At first I waited a while (+/- one hour) and the thing would start up again as if nothing happened.
After it started happening more frequently (or maybe I should say, 'after it didn't go away by itsself') I just didn't wait, but tried to find out what went wrong, and how to fix it.
All I have learned so far is that if -after a 'radical shutdown'- I release the levers on my processor's heatsink, and wiggle it a bit, then refasten them the computer will start up again, no problem. But ONLY if I disconnect the powercable from my machine ENTIRELY first.
I'm don't have the technical knowledge myself to make anything out of this, and am at my wit's end by now.
My specs:
mobo: 865PE-NEO2
mem: 512MB Pc3200 dual channel
processor: PIV 2.4GhZ
video: Radeon9700PRO
PSU: 400W
Also:
- All BIOS frequencies are at default
- Got six ventilators in a case that is always open.
- Got Corecenter running in the background with very tight temperature alert settings.
- I have no other problems with my computer, and I do not overclock.
All this at least leads me to believe it's not a power-, frequency- or heat issue. But then again, I'm no expert. At all.
Any help or insight would be greatly appreciated.
Thanks,
Juju

Answer 1

Is ur CPU OCed ?????
And whats ur VDimm, cuz i had the same Problem when running Gothic II with all details aon 1600x1200 2xAniso & 4xFSAA.
I believe the Problem is that ur RAM shuts down under full load if ur VDimm is too low, because all MSI Boards dynamically OC a littel (3-4 Mhz FSB) when running under full load (I read that on http://www.tomshardware.com).
On my system with standard Vdimm @2.5 V and FSB Oced to 250 my system would crash almost everytime when I played Gothic II. Then i found out that the board booted at 407 Mhz DDR Clock. That's when i started suspecting that my Rams couldn't handle 407 Mhz when running at an extremely low 2.5 VDimm.
So try the following:
-Increase VDimm from 2.5 up to 2.7 V in small steps and check ur system stability every time stop when everything seems fine.
-If u'r Oced don't go for FSB 250 (and multiplier at 5:4) try sth. like 243 so even if dynamically oced ur Rams won't go too far above 400 Mhz.
P.S.: My VDimm is now at 2.6 and FSB at 244 and everything is fine.