Help getting my 7970 past the 660khps barrier

[Spetznaaz]

Ignore this forgot i already posted

[Rave]

Hi,

I have a Gigabyte 7970 OC (GV-R797OC-3GD) and I'm trying to mine a SHA-256 coin.

Code:

cgminer -o stratum+tcp://server:port -u user.1 -p password --shaders 2048 --intensity 14 --worksize 256 -v 1

CC: 1100
MC: 800

Driver: 9.14
Catalyst: 13.1
CGMine4: 3.1


That give's me about 660 Mhash/s. Now, if I try to higher the core clock , let's say to 1150, my hashrate goes up to 690...but then, after 1 minute or so, my card crashes and I have to reboot. Any idea how to solve this problem? Thanks.