I have 2 PIII-700 machines running at 1GHz+ and I am using Alpha PEP66's on them. They are designed for slotket use, but on a socket board you merely turn the fan shroud 90 degrees and away you go. I originally had the Sunon fans, and when I upgraded them to the Delta 7000RPM models, my temps dropped 5 degrees. I never go over 35c now even running 2 concurrent Seti's on my dual processor machine.