With afterburner's latest version 2.2.2 it does not matter how high I try to raise the voltage with the slider, it won't actually go up. But, as I have said in several other posts, MSI has promised that voltage adjustment will be possible with this card on the next/future afterburner release.
Does the slider not work? What is the highest voltage you have to work with right now?
The slider will adjust but it's not affecting the GPU's voltage. The GPU will max out at 1.175 (under heavy load) whether or not the slider is adjusted by +12 or +100.