I had the same sort of problem with an Enermax adjustable speed fan.
The wire of the variable resistor is to long, it functions like an antenna
and is sending bad rpm info to the motherboard.
If you disable fanwarning in bios maybe the problem is not there anymore?
I shortened the wire to about 2 cm and put the resistor back on.
That did help for me.

"Builder" schreef in bericht
. com...
Using an GA-8IXP. The case fan has a speed control (variable resistor) on
the front of my case. The case fan gets it voltage from the MB sys fan pin
outs. When I turn up the speed of the fan the computer shuts down. When I
disconnect the speed control for the fan all is well but fan runs at only
about 1/2 its rated RPMs. I thought it was simply a bad speed control knob
assembly so I switched to another and had the same problem. Could it
possibly be a bad fan? Or perhaps a power supply or mother board problem.
Any suggestions would be greatly appreciated. It started shortly after
upgrading to new 3.06 cpu, an additional 512 megs of ram and a new DVD
drive. I doubt they are related but I guess I could have damaged something
when making these upgrades.

Builder