[mumbomum]

Ever since installing a GigaByte 990fxa-ud3 and an AMD fx6300 I have been getting random restarts and sometimes complete freezes from playing games (20-25 mins into playing bf3), transferring large files and even windows updates.

Things I have tried

-Trying with one 1 or 2 sticks of memory at a time
-Re installed windows and drivers
-Changed PSU
-Tried different GPU drivers
-Used different graphics card
-Tried different sata cables
-CHKDSK - 0kb in bad sectors
-Watched temps as i gamed (all seemed fine)
-checked for bios updates

Things I've noticed

-Windows 7 install has been a breeze every time
-No restarts or freezes when installing programs and drivers manually (might just be luck)
-Hard to trigger or know when the freeze/restart is coming. However it always restarts in BF3 after 20-25 mins of gameplay

How can I find out what is causing this problem? I am sure its either the motherboard or CPU but cant figure out which one!

SETUP

Gigabyte 990fxa-UD3
AMD fx6300 (stock cooling)
Gigabyte gtx 660oc
Corsair TX650 bronze
8gb G-Skill 1600mhz
1.5TB western digital caviar green
Windows 7 64bit (installed off USB because i have no optical drive atm)

Any help would be appreciated! Any program that records down what caused the restart? Thanks