type of fan required for motherboard connector

[wpshooter]

Does a case fan have to be a certain voltage, wattage, etc. to work/run from a 3 prong M/B connector ?

I have some old 8mm fans that will not run when I connect them to the 3 prong M/B connectors BUT they will run just fine when connected to a power supply connector.

Thanks.

 

[Cheezeit]

Well possessing an 8mm fan is quite a feat in itself as that is barely bigger than your pinky nail.

Any 80mm fan should run fine on a mobo connector, are you sure you have the fan headers enabled in bios? make sure the bios is not set to thermal control or something. Unless it is a really old motherboard, I highly doubt the motherboard cannot give out enough power.

 

[Billb2]

Originally posted by: wpshooter
I have some old 8mm fans that will not run when I connect them to the 3 prong M/B connectors

Reverse the polarity.

 

[wpshooter]

Originally posted by: Billb2

Originally posted by: wpshooter
I have some old 8mm fans that will not run when I connect them to the 3 prong M/B connectors

Reverse the polarity.

How do I accomplish that ?

Why would I have to do this to get the fan to work on the M/B connector when it works fine without doing this when plugged into the computer power supply ?

Thanks.

 

[grjr]

some fans can draw more current than a motherboard fan header can supply. If your fans draw too much current it is possible to burn out the fan header on the motherboard so that it will not supply power anymore. The fans should be labeled as to how much current they draw in Amps. Maybe post those ratings here to see if that is your problem.

 

[Billb2]

Originally posted by: wpshooter

Originally posted by: Billb2

Originally posted by: wpshooter
I have some old 8mm fans that will not run when I connect them to the 3 prong M/B connectors

Reverse the polarity.

How do I accomplish that ?

Why would I have to do this to get the fan to work on the M/B connector when it works fine without doing this when plugged into the computer power supply ?

Thanks.

If the (+) and (-) connections of a computer fan are reversed, the fan will not run.

 

[Zepper]

Generally the red wire on a fan goes to +12V and the black goes to ground, if there is a yellow wire, it goes to the speed sensor pin (i've seen other colored wires, but black, red, yellow are the norm). The red is generally the center pin with the black and yellow on opposite ends. The pinout of the mobo fan headers should be in your mobo manual if there is any question. the mobo header has a key on it which fits into a normal female fan connector only one way without forcing. Generally you want to keep any fans connected to the mobo under 0.5A (500mA or 6 Watts) each unless your mobo manual or mfr's site says otherwise.

.bh.