Hey,
 
I just purchased 2 GTX 680 2GB FTW cards and I am having a problem with 1 of my cards.  What is happening is when I run a 3d app my video card will randomly downclock to 324Mhz and I have noticed that the Power % is at 275% when this happens.  This problem only happens with one of my cards and this is with stock settings and two different drivers, 301.42 and 304.48.  My power supply is a Corsair AX1200.  I have tried the video card alone and it still randomly drops clocks to 324Mhz.  Not sure what to try to see if my card is bad.
 
Thanks.