yes, it is best to let the pump only run overnight at least to get most of the air out. You need to tip the comp back and forth and side to side some just to make sure you shake the air loose. I had a huge Swiftech heatsink on air and when I went to watercooling, I run about 12-15c cooler on the CPU, not to mention that I have everything hooked up to watercooling.