The blue wire is the tachometer lead for motherboards that have this option. Not useing it will not hamper the fans performance. Clint Worley Worley Technology -- Harvey Rose <[log in to unmask]> wrote: I'm replacing a power supply fan in a Pentium AT computer it has a red and black wire which I need to change the connector to the new one which has a red, black & blue wire. Do I need to connect the blue wire somewhere - is it a ground? Harvey Rose [log in to unmask] PCBUILD maintains hundreds of useful files for download visit our download web page at: http://freepctech.com/downloads.shtml ________________________________________________________________ The best thing to hit the Internet in years - Juno SpeedBand! Surf the Web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today! PCBUILD's List Owners: Bob Wright<[log in to unmask]> Drew Dunn<[log in to unmask]>