Miért indul újra a gép? (angol)

Üdv!

A kérdést már kiírtam egy angol fórumra, de nem kaptam pontos választ, ezért ide is kiírom:

Before saying anything, my PC:

Motherboard: Asus M4A89GTD Pro

CPU: AMD Phenom II X4 960T (No OC or unlocked cores)

Memory: 2 x Kingmax 4GB 1333Mhz

GPU: Sapphire AMD Radeon HD6950 1GB GDDR5 PCI-E

HDD: 2 x Samsung 250GB SATA 2.0

OS: Windows 7 Ultimate 64-bit SP1

Monitor: LG 22EN33S

So few weeks ago, while playing a PC game, my computer suddenly restarted, stepped into restart loop with no POST. I had to unplug the PC and do a CMOS BIOS reset. After I reset, everything went fine for a few weeks, but today, while browsing the web, the PC suddenly restarted. It had to restart twice to get POST, but it got back up. I decided to turn the PC off and wait till it cools down, it was running for hours already, thought might've been an overheating problem. I waited, when it cooled down, turned it back on, and 30-40 mins later, while watching a video, it restarted again, this time, I had no video after restart, the monitor didn't see any video signals. I had to restart it to get everything back.

1-2 months ago got the first ever BSOD on this PC, it was atisomething.smth, I guess the GPU failed there. Another incident, bit later, while watching a video, the PC froze the way that the screen totally froze and the sound went to distortion. Restart was neccessary.

Mi lehet a probléma pontosan?