i7 920 C0, need Diagnosis! maybe broken =(

specs in sig except for the overclock which is at 3.6ghz now (summer clocks).

let's get started!, My pc powers off (without even BSOD) when it reaches high cpu utilization,
not always but if i stay idle it just won't crash.

this can happen during windows loading (which got me thinking of some microsoft screw up) or playing.

Sometimes i can't manage to load into windows unless i revert to default CPU clocks while sometimes (like now) i am running at a confortable 3.6ghz again.

I have been playing around with settings as long as i could, but i should mention that these settings have hold up for nearly 4 years now and the problem happened the day after i have played BF3 and RAGE for 4 hours without a crash (both heavy cpu demanding).

this stuff happening so badly just the day after makes me wonder if my brother touched my pc but back on topic!

I never had a faulty part on most of my pcs till now. i don't know how to see if it's the cpu, the motherboard or the PSU.

Can someone please help me with some good stress programs?
I would keep it on default clocks and just wait till I buy a new pc, but fps loss in BF3 is near 15-20 fps without adding to it that it still crashes.
And i didn't even dare to try RAGE since it's fabulous UBER ATLAS is a cpu ***** like nothing i have ever seen before.

What are your temps while gaming with core temp? I would use prime95 and Intel Burn Test for stress testing. What is your memory clocked at? As some memory doesn't like clocking very well at higher ambient temps. Is your GPU overclocked? If it is it might be the problem as well. What are the BSOD codes you have been getting? This might go a long way in diagnosing the problem.

sorry if i shut you down early, but i need some more expert advice on this.

still you reminded me to tell temps. which never exceed 70 while gaming.
and memory @ 1400 mhz.

I know for sure it is not a GPU problem, since the pc powers off even during startup (way before drivers get loaded)

as i have already mentioned, the pc doesn't BSOD it just powers off.

I hope someone had some similar problem once and is willing to share =)

I'd say either a PSU issue (1250W is a lot, but might be faulty, who knows?), or MoBo?

A broken CPU just doesn't boot usually.

ok weird, it might have been one loose gpu.

i was checking again, trying some different overclocks, when i boot in fine, load BF3 manage to start up the campaign. after a while i noticed the fps wasn't what it used to be. so i check the gpus, and i find out windows recognizes only one of them

(I panic ofc)

then proceed to reseat the gpus and see if any luck.
everything works like a charm now as before, i am still concerned about all this though =(

i hope my beauty doesn't break for good one of these days

As the first guy said, I would try IBT or Prime 95 Blend to test stability.

If the reseat worked, good for you that's great. It might have be chip creep and a good reseat is always a good idea in a situation like yours.