Someone please help with my mobo/PSU problem.

Hello people I'm really frustrated as my pc has just destroyed my second motherboard. (well at least my pc doesn't even load bios and no beep sound and my monitor has no response when the power turns on).
Firstly I had a problem cause my CPU fan wasn't on tightly enough, I fixed that and CPU stayed at 35 degrees C. Anyway a bit later my pc randomly restarted when I played games for about 15 minutes. There was never any lag and my pc was on ultra settings for the games. so I bought a new mobo (the same one) and it fixed the pc not loadin up but not the restarting issue.
I just tried removing one of my 4GB ram sticks to see if I would fix the issue. My pc restarted much faster than usual. Then I tried with the other stick. Now my bios doesn't even turn on... Has my mobo been destroyed again?
I tried removing the mobo battery to reset it, but nothing happened.
All my fans are working and everything seems to have power, but it doesn't load up.
I guessed my PSU fried it?? Also i made sure not to touch any parts to avoid static damage... Can anyone help me?

My system:
Asus p8p67 motherboard
I5 2500k CPU with mugen 3 heatsink
4G patriot ram x2
Nvidia gtx 570 graphics card
750 watt power supply