> Motherboard: Foxconn N570SM2AA
> CPU: AMD Athlon 64 x2 5600+ AM2
> The CPU has a 4-wire fan (black, red, blue, yellow). The "CPU Fan"
> header on the mobo only has 3 pins. Using the polarization on the
> connectors, the black, red, and blue wires would get connected while the
> yellow wire would hang off by itself and not be connected. From what I
> can tell, the 3 wires that would get connected are power, ground, and
> sense. It would be the PWM (pulse-width modulation) wire that wouldn't
> get connected. That means there would be no control on the speed of the
> CPU fan. The assumption is that without this control, the fan would
> constantly spin at its highest speed but others have noted that without
> the PWM line connected means the fan might spin at high (noisy), medium,
> or low speed - and low would probably be too little to properly cool the
> The mobo's manual shows a 4-pin header for "CPU Fan". That is NOT what
> is on the mobo which only has 3 pins. Next to the 3-pin "CPU Fan"
> header on the mobo is a 4-pin "J4" connector. It is bare (just the 4
> pins in a row and no plastic polarizing body). The J4 connector is not
> mentioned in the hardcopy of the manual included with the mobo nor in
> the online copy of the manual. So while J4 has 4 pins with no
> polarizing plastic body and is next to the 3-pin "CPU Fan" header, I
> haven't been able to determine is that is where I plug in the 4-wire CPU
> For a picture of the mobo, look at:
> It shows a 4-pin header for the CPU fan. What I actually got on the
> mobo is a 3-pin header marked "CPU Fan". The pictures are lying. The
> specification for that mobo says that it supports 7 (seven) internal
> SATA ports and which I have. There are only 6 shown in the picture. If
> you look closely at the picture, up by the 4-pin Molex connector on the
> mobo is a square chip and right by it are solder pads for the 7th SATA
> port missing in the picture but is on my mobo. Also, the specs say
> there are 3 internal USB headers, not the 2 shown in the picture (the
> 3rd is where the solder pads are in the lower left of the pictured mobo).
> Remember the "J4" labelled 4-pin header that I mentioned might be a
> possibility for connecting the 4-wire CPU fan (just a guess, though)?
> Nope, it's not in the picture but the solder pads are there in the
> picture (to the right of the *pictured* 4-pin CPU Fan header and
> underneath the tall black heatsink).
> Apparently when Foxconn decided to upgrade this mobo to add the missing
> connections (since the chips were probably already there) they chose to
> change from a 4-pin CPU Fan header to just a 3-pin header. That sucks.
> Now I have to figure out if I want to return the mobo to Newegg and find
> a different one or figure out how to get the PWM function of the 4-wire
> CPU fan to work with a 3-pin header (or find out what the undocumented
> J4 4-pin header is for).
This article is from Intel and is specifically about their motherboards
but it should apply equally to others: http://www.intel.com/support/motherb.../cs-012074.htm
If your motherboard supports fan-speed control on the 3-pin connector
then it should work with your 4-pin fan. The method used will be
different and possibly not so precise but it should still work.
[Knoxville, TN, USA] http://johnmcgaw.com