hows this for a crazy power problem

**jak** · November 23rd, 2002, 03:13 AM

so i install some switches, one controls two fans the other controls a cold cathode, when they are in on positiion the computer is fine when the cold cathode is in off and the fans are in on the computer is fine, but when i turn off the fans, the whole system just shuts down, immediate power loss, so where is teh prob?? this doesnt make any sense at all
jak

**Peter M** · November 23rd, 2002, 11:21 AM

Are the fan speeds being monitored by the mainboard? If so, chances are it'll turn the system off when detecting a fan failure.

**MDS** · November 23rd, 2002, 11:24 AM

I would guess the same as Peter or the switch is shorting the psu.

**Tomteriffic** · November 23rd, 2002, 11:46 AM

Some motherboards, particularly Athlon types, require that there be a spinning fan on one or more of the mobo fan connectors. If they sense zero RPM on these connectors, they'll shut down pronto. Typically it's the connector that is intended for the processor HSF, the idea being that if your processor cooler fails, you have about 5 seconds until your chip is toast.

So, if one of those fans is drawing its power from that particular connector, there's your problem.