Something i noticed with the 79** series is that some are very particular with overclocks, mine can only do 1100 on the core and 1550mhz on the memory any higher and the card drop fps by about 5-10fps. Is the card still boosting in game? it is a ghz edition, and want to make sure its not trying to clock higher that would mess it up. Also you can just drag the slider up to 20% for the power, it should be just fine. and you take a gpu-z screenshot and upload it so we can see.