Speed can be adjusted manually with a control dial mounted on a PC backplate
 
PaxPower Ultra Quiet Amber fan
  
All copper fine-fin heatsink
AK-859 AMBER SERIES COOLER
Designed for Socket 754, 939 & 940
AMD Athlon 64, 64 X2, FX-55, FX-57, Sempron & Opteron.

Ultra quiet Amber Series AK-859 is a new 80mm amber cooler for AMD Athlon 64, 64 X2, FX-55, Sempron and Opteron. Twin ball bearing Amber fan ensures Ultra quiet reliability and long life. The anti-noise 3D fan guard reinforces the ultra quiet experience. A pure copper heatsink provides rapid heat absorption. The manual speed control also allows you to control the fan speed.
PaxPower Ultra Quiet 80mm Amber fan
Pure copper heatsink
Manual speed control on PC backplate
Anti-noise 3D MAX AIR fan guard
  Socket type   AMD Socket 754, 939, 940 & AM2
  Heatsink dimension   84 x 80 x 45mm
  Heatsink material   Pure Copper
  Fan dimension   80 x 80 x 25mm
  Fan speed   2000 - 4000 R.P.M.
  Fan airflow   30 - 59.8 CFM
  Fan air pressure   1.5 - 5.4mm H20
  Fan life expectancy   75000/hrs
  Bearing type   Twin Ball Bearing
  Voltage rating   12V
  Noise level   23.5 - 43 dB(A)
  Product code   AK-859
PC Backplate for speed control
Manual Installation
Installation Manual
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Xtremecomputing.co.uk

 "would go as far as saying this has to be the best performance I have seen come out of a air cooler in a while." more..

Custom PC

"The AK859 is very easy to fit and because of its variable speed fan its suitable for both non-overclocked quiet PC's and overclocked speed demons."