The H100 is tricky to install correctly, I think the mounting brackets and hardware are poorly manufactured, every one seems to have one position that actually has good contact between the sink and the CPU. Try mounting it again, using a cheap thermal compound on the CPU only (radio shack has a ceramic compund for $5 for a big tube). pre-spread it with a baggy over your finger, a spreader tool, a credit card, or whatever method works for you to get a super thin layer over the entire CPU and the CPU only. Try positioning the sink/pump.controller combo and see which position leaves the most compound on the sink surface. Clean the cpu and sink again and use the same spreading technique but with a high quality metallic type thermal compound like arctic silver. Mount the sink in the best position again: hold it fast to the CPU while you get each thumbscrew just to the point where they meet the mounting brackets, then turn two screws at a time, a half turn at a time till they will not possible tighten any more. switch screws every half turn: tighten top left and bottom right a half turn at the same time, and then the bottom left and top right a half turn at the same time, repeat.
I have installed a bunch of these, this is a reliable way to get good performance out of the H100. if installed correctly it performs very well.
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