Windows 7 random crashes

[Craved]

Hoping someone could help me resolve the following issue that I've been having over the course of a few months.

Issue: Computer randomly restarts without warning just kills off.

- Crashes when booting from time to time & after login screen, before Windows logo shows. (even first time booting on the day)

Confusion: When I do I get it started after a few failed attempts I can be on it for a given amount of time before I have any issues.

Example: I can play games on it for hours and it wont shut down. (LoL/L4D etc)

Specs - Computer is outdated-*

Processor: AMD Athlon 64 x2 Processor 6000+
Ram: 6gb
Operating System :Windows 7 Ultimate 32 bit
Video Card: ATI Radeon HD 4670
Mobo: Gigabyte GA-M61P-S3

I've Tried: Checking all wires to make sure they've been connected properly, cleaned out computer case 0 dust, tried multiple HDs same issue. Resetting bios allow me to boot up without fail.. Could it be bios?

 

[Frozwire]

Have you tried checking your RAM and HDD with some utilities to rule out some possible issues? You might also need to check/monitor your hardware temps to find out if any of your hardware is having unusual behaviors.