I have an F2A88XM-D3H motherboard, there is no way to set negative value in Voltage section which is a really annoying issue since almost all other manufacturers include this feature in their UEFI.
FM2 apu's are doing very well when it comes to underclock my CPU default is 3600
MHz@1.35V, I can reduce voltage with Overdrive to 1.15V and still stable, the temperature is 10C less compared to stock.