PC broke down

[tom adam]

I could need some assistance ;-)
I've got a HW problem with my PC which makes it unusable ;-)

Symptoms are as follows:
It starts up Ok, but after a while it just stops working (power goes 
off). After a couple of seconds it reboots automatically. First time i 
tried it goes down after +/-5 minute, the second time is much faster. 
When I wait for a while it takes again about 5 minutes before it stops.
Also, I can normally start the PC by pressing my ancient keyboard. 
That's not working any more.

System is a 4core i5 whathever processor and a ASUS P7P55D, 4gig ram, 
1000gig standard HD.

What I've done today was checking the temperatures and voltages in the 
bios screen. voltages are OK. I notice that the temperature goes up to 
60c at 62c it shuts down. I removed the heat paste from the processor 
and put new heat paste on it, now the temperature stays at 42c, but it 
still stops working after 5 minutes. I've also checked the led's as the 
MB manual indicated and apparently I have no problem;-)
Than I took out all the cards I don't really need (M-audo delta1010) and 
used a USB keboard, no changes in behaviour.
Than I replaced the video card with an old one, still the same.
After that I decided to walk away as I was getting too frustrated.
Now I'm calling the Bar...
Cheers,
ToAd (Going to look for a laptop that runs ubuntu studio and a new audio 
interface, any suggestions?)