Ok, so here is the whole story.
At first my PSU died on my old computer, but since i didn't realize that, i thought it was the motherboard, so i bought a new one.
Then obviously with the new mb comes a new proc and new video card and the new PSU. Then i started getting weird restarts, and i couldn't even install windows (it would just restart by itself on random occasion). Then i started thinking it was the memory, so i bought that also, but alas it did not help.
So now i have a brand new computer:
Pentium D 3.2GHz + a fairly strong and big fan
1GB DDR 3200
GeForce 6800 256mb
80 + 40 gig hard drives (freshly formatted)
.. that doesn't wanna work.
Eventually i managed to install windows, and the restarting appeared to have stopped, but as soon as i started playing games, or doing anything that needs more power from the computer, it would restart.
Now, i've been looking EVERYWHERE for a solution. Keep in mind that I:
Have no dust in the case.
Have checked all the cable connections
Have reseated everything that can be reseated on the motherboard.
Have tested: 2 different video card, 3 types of memory, 3 power supplies, 2 windows' (xp and vista), different power cables and different power sockets in the wall.
Now, all my new hardware is brand new from the box EXCEPT the CPU that is refurbished (after 7 days from original sale, apparently the customer changed his mind).
I don't have enough money to replace the CPU for now, so i would really appreciate any suggestion you guys can give me.