I own the H100 with the grinding noise
First I tried what's suggested on corsair forums which is laying the computer on its side for a while and gentle hits on the pump and tubes in case its because of air.
I noticed that the pump was quiet when the computer was down on its side but as soon as it was back to normal position the pump was back to the grinding noise.
I RMA'd the H100
Received the second one a few days ago, same grinding noise, and again no noise when computer on its side (I'm starting to think it was designed and tested only in that position before going retail

)
Today I tried the diode fix, which dropped the RPM from 2163 to 1953 but it didn't go quiet like other peoples here.

Just got a 2nd RMA approved (fortunately I don't pay shipping for RMA with NCIX).
I don't mind doing RMAs as I still have the cooling that came with the cpu and as long as I don't pay for shipping (thanks to NCIX) but it's a bit a pain in the a.. to get the radiator in and out of the case everytime.
I wish the next one will be better or that at least the diode fix will make it quiet, I like the look of the H100 in my case.
BTW Thanks to wlw wl for sharing its knowledge !
