I installed my volcano 12 last night. Initially, I had the fan speed controlled by the rheostat that fits in an empty 3 1/2 in. bay. I had the fan speed set at about 3500 rpm and was surprized at how quiet it was. It was giving me idle temps of 38 C at that speed, about 2 C cooler than the cheap all aluminum hsf I replaced it with and with somwhat less noise. During the night the rheostat must have given up the ghost because this morning the volcano 12 fan was turning full bore. I quickly ascertained that the control was bad as turing the knob had no effect on fan speed. So, I switched over to the under the cpu temp probe auto control and at a fan speed of about 3000 rpm (very quiet) I am getting an idle temp of about 40-42 C and less delta under load than I was getting with the aluminum hsf. Of course, the Arctic Silver 5 hasn't had a chance to cure yet, so I expect the temps to be even a little lower a week from now. Summary, a little cooler and considerably quieter with the Volcano 12.