i have a h100i and my temps are always good. the khuler 620 is not very good. is there a reason you need your volts so high? if you are set against the AIO, then i again recommend the noctua nh d-14
The reason my Volts are so high is because my FX-6300 @4.8Ghz require more then 1.5 volts to stay stable, its like you said it all depends on the silicon lottery, And my picking was a bad apple LOL, If anything happens at this voltage setting and it blows up then its ony 140 to replace but then again like the new 6350 came out so ill pick that up!!!
BTW Its running on the evo right now and my higest temp is 58c on the evo 212 so it seems good so far, on idle im at 25c most of the time and im at 4.8 GHZ and I love it!!!!