PC rebooting put of the nowhere

[Noc616]

My pc reboots out of the nowhere, but specially when i try to encode videos to MPEG-1 with nero, and then it wont boot.
Is it my Ram or my video card.
I have 2*256 pc133 kingstone and a radeon 9000@128mb with the latest drivers on windows xp pro sp2.

Thanks

 

[Bushman5]

It Could be heat
You Ps would be also failing.


Check the fans on your pc make sure they are not cluttered with dust. Also check the temperatures of your devices during heavy operations

 

[Muscles]

Download memtest to check if you get any errors with your RAM.