Just out of interest I thought I would ask this as my 1.4Ghz Athlon at 1.5Ghz with a Y-Tech 4000 rpm fan is reasonably loud. I wouldn't like to consider the noise necessary to overclock a chip from 1.6Ghz to 2.2Ghz with air cooling (600Mhz!!). I used to have Delta Fan on my SK6 heatsink but it was unbearable and I seem to get loaded temps of about 40 degrees celcius with the lower specification fan so I am ok with my 100Mhz overclock (via 133 fsb -> 143 fsb, A7M266 doesn't have multiplier dip switches or bios settings). One reason I have always considered Intel CPU as an alternative to my beloved AMD chip is the ability to run cooler and therefore require a less deafening HSF. So does anyone currently have a P4 overclocked significantly (Particularly the "a" northwoods) and can provide any information about the cooling that they need?