Back again

Alright well this time it's with my new rig (clicky the My PC thingy to see specs). I installed a Zalman HSF (Newegg.com - ZALMAN CNPS7700-ALCU 120mm 2 Ball CPU Cooling Fan - Retail) and it worked really well, brought temps to 25 on load, so I ramped the CPU up to 3.23Ghz and it was running fine under load at a maximum of 45 degrees (celsius). Then all of a sudden, today, it randomly shut down while playing Supreme Commander. Intrigued and wondering why my computer flipped off, I tried turning it back on, but it wouldn't turn on, waited 15mins, turned it on, checked the temps, read 30, booted back up, browsed the ent a bit, ran a stress test (Prime 95), and re-launched Supreme Commander once I was satisified it was stable. It shut down again, booted back up, tried Bf2142, same thing. Now rather annoyed, I booted up, and ran StarCraft, and again it shut down! Now completly confused, I ran it, and setup my second screen to show me temperatures, and I saw it was idling at 50 degrees and would go to 52 on load, and rocket to 70 and shut down.
So I dropped it back to stock (1.86Ghz), and tried again, except I noticed something strange.. The temperatures were the same, so I went into BIOS and checked the voltage settings, but they were fine. I lowered them a bit just to be safe, booted up, same temperatures. Started a game, went to 52 degrees, and then rocketed to 70 and shutdown.

I took off the heatsink, cleaned it, put new artic silver on it, and tried again. It keeps doing it, I even tried the old stock cooler I still had, and the temps were even worse. I'm at a total loss as to why it's doing this. Ambient temperatures are about 70 to 76 degrees farenheit and the case is well ventillated with a bunch of 120mm fans and it's in an open area, I even opened up the case.

Help..

(I've managed to get it to idle at 47 currently, but as soon as I load something up, it'll idle at 50 again)

Well that is strange...

It's almost as if your video card might be overheating and the computer is reporting false values for the CPU.

Check the fan on the GPU to make sure it's spinning.

Thanks for the reply,

The vid card is whizzing along happily at 59 degrees, I've stress tested it, and it works fine and the temperature don't conflict since the card goes up to 75 degrees under maximum load and the CPU isn't used (video stress test only)

Hrmm....ok, when you pulled the HSF and cleaned the thermal grease, did you see any damage done to the cpu at all?
I know if there's a crack in the top - sometimes they still work, but only at a fraction of there previous performance and will overheat in an instant.

There wasn't any physical damage that I could see or feel. it works perfectly fine, just that it heats up randomly for no reason, it's still going as fast as it's always had, Windows doesn't report any problem, Prime95 is happy with it, CPU-Z reports it's OK... It's weird :S

mmmm....
Ok then...the usual stuff has to be done then. BIOS update and chipset drivers - have you tried either of these?

I have the only releases NVidia and eVGA have made so far, they're still marked BETA updates, I'm waiting on them releasing the stable ones, but I just checked just to be sure, and I have the latest =\