PC freezes when playing games?

So every time I play games for about 1 second - 5 mins my PC will hard freeze, making me have to hard reset!

FX 4100

HIS 7870

600W PSU

Gigabyte m68mt-s2 MB

So I have run CC Cleaner

Installed new drivers

and tried to clean as much dust as I can! 



If is not RAM error, or overheating, i suspect on Motherboard.

PS: Edit your post, a lot of "<p>".

I have bencharked FurMArk at 1080p for 15 mins .. perfect