I tried to overclock my 7970. My card is sapphire dualx (blue PCB) and yes I can unlock the voltage.
I can see others getting their OC for as high as 1200MHZ in core and 1700+Memory. Without touching anything on the voltage, mine can unlock 1080 and 1600 respectively. The moment I unlock, in order to get 1125, I have to max out the trixx which is almost at 1.300 reported by GPU.
my PSU is a cooler master Extreme powerplus 550W. I'm using a 3570 non K, 4 sticks of RAM, 3 HDD, and total of 2 Fans.
If I change my PSU, could it be the factor that I can't get the OC stable?