Random Reboots no BSoD

[JDyer]

I have a strange issue with my computer, often times I will hear it reboot from the other room, while completely idle, and sometimes while doing something else such as in a game or just on the internet. It does seem to happen more when idle though.
Also, sometimes whenever I reboot my computer it will boot until it loads the desktop or user selection screen then reboot again. It'll ask to repair start up but then it will do nothing and after an hour notify me that it simply cant repair. It will sort itself out around the third or fourth reboot, with or without check disk or repair start up. Sometimes it will get to the desktop then restart after a couple seconds.

There is never a BSoD, or any error message when it comes back (usually a program telling me it couldn't start) or crash logs. I have a theory of it being a memory issue. Yes I have tried repairing Windows, but even with the correct repair disk it'll tell me that it isn't the right version. (win 7 x64)

Specs:
AMD 8320
GA FXA 990 UD3
GA Radeon HD 7850
2x Corsair 4gb
Seagate 1TB SATA
(cant remember manufacturer) 750 mb SATA with OS
None of it is Overclocked.

Sorry if this is in the wrong area, I didn't see any specific help category and I am not sure where my problem lies.

 

[Supahos]

Possible issues are:

1)power supply to small or failing (list your PS and how old it is)

2) your OS is corrupt and locking up randomly

3) you have a stick of memory going bad, try Running memtest on each stick by itself.