The third wire is for voltage/temp/speed control and is required. Fan is driven by circuit sense of CPU temp- speed versus voltage determined by temp. Try Japan-servo or Sanyo-Denki 3 wire 12V fans. BTW i have an AS800 for pick up in LI NY, (3) 9.1GB drives 400MHZ box. e-mail me at melk@switchpwr.com. Mel