6950 Problems.

Hi Everyone, new to this site, but lets get to the point here are old specs with the same card and new specs with the same card and the problem i have.

old specs

ASUS M4A88TD-V EVO/USB3
AMD Phenom II X4 Quad 955 Core 3.2GHz
Corsair TX Series, 650 Watt
G-Skill 4GB Ripjaws X DDR3 1600
Windows 7 64bit home
XFX HD 6950 1024MB
Monitor is an LG 24"

New specs

Gigabyte 990FXA-UD3
AMD Phenom II X4 Quad 955 Core 3.2GHz
Corsair TX Series, 650 Watt
Corsair 8GB 1600MHz CL9 DDR3 Vengeance
XFX HD 6950 1024MB
Windows 7 64bit home

Ok the problem is the card crashes after a few minutes into solid color screens gray, black, or blue sometimes black with grey veritcal stripes. Programs run but the display will disappearand sound still plays. Mainly crashes when idle or browsing the internet for a few minutes, it works for an hour or 2 when playing a fullscreened games. The temps on idle are 35c to 50c and underload around 50c to 75c. The cards clocks are set to default nothing is touched just installed the card and the drivers.
The card has been sent in for testing and has come back working, so i need you lovely forum people to help as im no computer wiz.

Thanks Smudge.