Unlock Voltage Control on XFX 7970 DD?

I have a XFX 7970 DD and The max overclock I can get with Catalyst is a mere 1040Mhz Core and 1500 Memory (Stable 24/7 on all games, I can push for like 1080-1100 in games like Minecraft w/ shaders but in BF3 it crashes almost instantly)
I want to use another program to get around 1100+ on my core and no matter what program I use the voltage control is locked. I've looked up guides on how to unlock the voltage control on things like MSI afterburner but even when I do those nothing changes at all. The voltage control is still greyed out or not even present.

I really have no clue what to do at this point, I go crazy when I'm not playing a game at 60fps, I just can't do it, and the only way I can fix this while playing BF3 is by turning off the AA, and with a 1080p 27" monitor the jaggies are killing me.

the voltage is restricted in the card bios, in order to unlock the voltage, you will need to flash your card with a bios that allows voltake ajustments. It is a risky think to do as you could end up with a bricked card. I would just leave it as it is.