XfX 7970 Black Edition unstable under manufacturer overlock

Hello

I have a brand new 7970 BE and i have crashing issue in games like BF3 and Shogun total war when the graphics are turned up to ultra. The game will freeze within seconds of launching in BF3 and after couple of seconds after entering battle map in shogun.
The screen goes black and then sends me back to desktop with "display drivers stopped working and has recovered successfully."

Furmark stress test at manufacturer over clocks runs fine so does unigine heaven at max settings possible.

I have tried to under clock the card to vanilla clocks so down from 1000/1425 to 925/1375 and the game run fine.

I have updated to CCC 13.2 beta but i have tried 13.1 before, all fail.

I have a 750W corsair power supply so is it possible that the power supply runs out of juice ?

rest system specs are

I7-930k at 3.9ghz
12gb 1600mhz ram
2x 7200Rpm HDDs
samsung 830
Mouse, keyboard and gaming pad all draw power from USB.