I'm hoping to find an answer to the iGPU side of the APU as well. I have an APU 6800K that when I try to up the iGPU it just crashes no matter what settings I use.
As a response to ruizpect. My CPU side sits at 4.9 with a cpu voltage of 1.55 and runs stable through a full 3 hour prime 95 test under air cooling (cooler master Hyper evo 212 with a push/pull configuration). Best thing to do is just keep bumping your voltage up a notch at a time until it becomes stable. The higher the multiplier, the higher the voltage will need to be, 1.4-1.45 voltage will work for ranges 4.3 GHz to about 4.6GHZ, anything higher and your looking 1.5-1.55