The Dell fan has a feature that notifies the BIOS in the event of a fan failure. Third-party fans do not have this, thus your message. The trick is to jumper the socket on the motherboard where this fan sensor plugs in. With enough resourcefulness, you should be able to find information on the internet to do this. That's what my son did when he replaced the Dell fan on his (now my) 4550.

 If you have a disable keyboard error reporting in your BIOS/System setup, try that.

Disabling the keyboard error function does not help, unfortunately.

I've heard other people say it does'nt work. But my BIOS supports it

Message Edited by onion721 on 08-30-200607:52 PM

All you have to do is transfer the OEM fan connector to after market fan enabling you to plug it directly into the MOBO thus eliminating the fan fault.

Message Edited by onion721 on 08-30-200607:54 PM

Dell fans send a tachometer signal back to the motherboard.  Aftermarket fans don't necessarily do this.  If the tach signal is missing, it triggers the 'previous fan failure' message.  You may need another aftermarket fan that definitely has the tachometer feature.

Both my Antecs and Zalman HSF that are connected via the MOBO have RPM readouts.

I also had Maddogz that were read.