Computer Randomly Freezing! Help!

[sirDante666]

So I had a power outage recently, and after about five minutes to less than an hour of use, the pc will freeze. No BSOD.

After repeating this cycle a few times, I decided to roll back a week before the power outage. Same freezing issue.

Then I got my Windows 7 Ultimate disc, rebooted my computer, /eraseall/ the HD, and re-installed Windows. The PC did not freeze. It completed the eraseall command, which took about 9 hours for my HD. Windows was installed. Everything looked great.

About fifteen minutes after the installation was complete, I was enjoying web browsing, and then it froze. No BSOD.

Then I tried taking out the RAM, restarted with different combinations. Same result, whether it was one stick or four.

PC temps are normal between 35c~45c (based on the MOBO and SpeedFan)

I'm thinking it might be the motherboard. I recently tried to re-install Windows just for the hell of it, and when I get to the installation screen, my USB keyboard will not work unless I unplug it then re-plug it again. And the installation won't complete. I'm currently typing this from an older laptop that works alright.

I tried listening to my system while it runs, and everything sounds normal. HD sounds quiet. PC overall is quiet.

Any suggestions would be greatly appreciated!

Edit -----
I forgot to mention, I had a old Raidmax 500 Watt PSU lying around, and I did try the same troubleshooting steps as above with it, and no fruitful results.
-------------

PC Specs:
ASUS M5A88-V EVO AM3+ AMD 880G
AMD FX-8120 Zambezi 3.1 GHz Socket AM3+
Crosair 600 WATT PSU
Lite-On DVD Burner SATA
Seagate Barracuda Green ST1500DL003 1.5TB
Kingston HyperXBlue 4GBx2 + 8GBx2 DDR1600
Saphire Radeon 7700 1GB GPU
Windows 7 Ultimate

 

[Smoove910]

is your RAM voltage set to 1.65v?

 

[denis280]

4GBx2 + 8GBx2 DDR1600

and only use the 8gbx2...right now your system is working quad channel with (not matching dram)

 

[sirDante666]

I tried only using the 8GBx2 and that didn't work before. However, I did check the voltage...for some reason, it was set at 1.48~! @_@ I manually set it to 1.65v with the 8gbx2, and now I'm finally able to do everything.

But then, I tried adding those 4GBx2....your right. That messes things up too. I'll just keep those away in storage.

I can't believe I overlooked something so simple. It's a good thing I have my important data on a USB HD, so I didn't lose anything important.

Appreciate the help!