I have a Sapphire Dual X HD 7970 and can overclock fine and adjust the memory and core voltage using Sapphire TriXx, but I prefer GPU Tweak's layout. I cannot get GPU Tweak to give the option to adjust either the memory or core voltage. I've tried MSI AB and I can adjust the voltage but that doesn't even allow me to go past 1125mhz on the core so I gave up on that even after I enabled unofficial overclocking and copied the old driver files over. Any help on GPU Tweak or is there a modded GPU Tweak available?