4 Pin CPU fan with 3 pin motherboard

[SpitfireAce]

Hi,
I just bought an Core 2 Duo E8400 and the CPU fan that comes with it has 4 pins while my motherboard only has one or two 3 pin slots. The motherboard has the right socket, 775. I have googled and found out that some have managed to fix it by letting the blue wire from the fan be disconnected while the other three are connected. This did not fix my problem, the fan simply won't start. I haven't found any adapters either. So... any ideas?

 

[Nik_I]

are you sure that you're plugging the fan into the cpu header and not the case fan header? i can't think of any motherboard that doesn't have a 4 pin cpu fan connector. and even if it is only 3 pins, the fan should still work without having to re-wire it.

 

[SpitfireAce]

Thanks for the quick reply!
I'm not an expert on this so, what is the cpu header and case fan header?
I can't seem to find any 4 pin connecter on my motherboard :/.

 

[amd_overclocker]

The headers are just the pin slots on the motherboard. the motherboard could control the speed of the fan depending on the heat of the cpu. other wise they mostly will just say the speed of the fan

 

[SpitfireAce]

Right, I have a 3 pin header but even if I dont connect the cable that lets me control the speed, it doesn't work.

 

[dragonsprayer]

buy a fan header for 99 cents at SVC or other and cut it - then splce - 3 pin hsf like magic

the last pin is the speed control pin first 3 are power look at 4 pin mobo in picture

any mobo with 3 pin fan header can not be a good mobo!

 

[Reynod]

Power up the cpu fan (which in this case must have a 4 pin molex connector because no mobo can deliver enough current to drive a high powered cpu fan) and run the sense wire from the fan (splice it in) to a 3 pin header on the cpu header on the mobo.

Problem solved.

I must say usually the manufacturer gives you a 3 pin sense wire to goto the mobo where the cpu fan is a hefty one?

Remember the old fans on the thermaltake volcanoes ... like the 11+ ?

You wouldn't run them straight off the mobo or risk frying the fan circuit.

 

[SpitfireAce]

The fan does not have a 4 pin molex connector, this one is much smaller.
How do I power up the cpu fan? Do you just mean turn it on or increase its power in some way?

 

[Reynod]

Plug the small 4-pin connector to the "CPU-Fan" 3-pin on your motherboard. The connector has a tab that will leave the blue wire from your fan unconnected. This blue wire is the fan speed sensor. Reboot your pc and press the DELETE key to go into the Bios Setup. Disable the "Smart CPU Fan" and save/reboot. Your CPU fan should now run full speed, because when you disable "smart cpu fan in the bios, your motherboard will provide full power to the "CPU Fan" connector.

 

[SpitfireAce]

Do I have to install the processor first because I am afraid that without any cooler, the processor might break.

 

[Mizoguchi]

No, I had the same problem as you (and still do to an extent since I had to sacrifice my fan controller to get another computer working). The CPU isn't used enough when in BIOS to do any damage. Once out of the bios, my computer didn't let itself start booting up because it knew the CPU fan was not installed correctly, so I'd assume that your board would do the same. Anything in the BIOS should be fine for you.

 

[Guest]

I just solved the 4 pin cpu cooler/3 pin header situation...

Just snip the cooler's blue wire.
The cooler turns into a 3-pin version and runs at the standard rate, just as if you had bought a 4-into-3 adapter.

My MB wouldn't let me turn off the variable fan speed thingy in the bios (option was greyed out) but snipping the blue wire fooled it.

 

[Guest]

this solution didn't work for me... At startup my MB (Bios) complained that the CPU cooler was faulty and it shut down the machine.