I have 2 ASUS 970s in SLI and I tried MSI afterburner, EVGA Precision X, and ASUS GPU Tweak. ASUS GPU Tweak was the only program to accurately report the voltages and change them. Afterburner and Precision X showed the wrong voltages and would not change them.
 
Does anyone know if there is a fix for Afterburner or Precision X, because GPU Tweak looks so bad? Also, why does GPU Tweak not have an apply overclock profile on startup option? That's ridiculous.