My computer randomly restarts when playing games

[scotta1212]

I have had my computer for over a year now. It started crashing within a few months of getting it. I did a reinstall of the graphics drivers by using driver sweeper first. This got rid of the problem but a few months later it started happening again. I updated the BIOS after this and again, it solved the problem. Recently however, it has started again and I can't find anything that will fix it. Crashes generally happen when playing games like SC2 and ArmA 2 and a BSOD screen isn't given on reboot - I have auto reboot unchecked.

One extra thing to note: I recently removed my sound card and its drivers. Before this, the crashes were accompanied with a loud buzzing noise. Afterwards, it seems like the computer is just performing a regular restart, when it shouldn't be of course.

SPECS: Processor (CPU) AMD PHENOM II X4 QUAD CORE 970 (3.50GHz/8MB CACHE/AM3)
Motherboard ASUS® M5A78L-M/USB3: M-ATX, USB 3.0, SATA 3.0Gb/s
Memory (RAM) 4GB SAMSUNG DDR3 DUAL-DDR3 1333MHz (2 X 2GB)
Graphics Card 1GB NVIDIA GEFORCE GTX 550 Ti - DVI,HDMI,VGA - 3D Vision Ready
Memory - 1st Hard Disk 1TB SERIAL ATA 3-Gb/s HARD DRIVE WITH 16MB CACHE (7,200rpm)
1st DVD/BLU-RAY Drive 24x DUAL LAYER DVD WRITER ±R/±RW/RAM
Power Supply 450W Quiet 80 PLUS Dual Rail PSU + 120mm Case Fan
Processor Cooling STANDARD AMD CPU COOLER
Sound Card Sound Blaster® Audigy™ SE (since removed)

The minidump file says it was caused by driver: ntoskrnl.exe.

I monitored my temps and found that the highest gpu temp was 75 and the cpu was 62. When it did crash the temps were not at 75 or 62 and the 12V rail was still providing 12V. I managed to play ArmA 2 for 3hrs then SC2 for 2hrs perfectly fine until it did another random restart.

 

[yodap]

Just a stab in the dark. At first glance it seems the power supply may be a bare minimum for your system. If you can afford to blow $25 or so on a Kill A Watt meter to monitor your draw at the wall while you are gaming it may tell the story. It's a great tool to have for many things in your house and it will give you a better understanding of your computer.
Like I said, just a guess and I hope I'm wrong.