What's the difference between 3- and 4-pin power connectors ?

[NoobyDoo]

Fan power connectors can have 3 pins or 4. What exactly is the diff / advantage of one over the other ?

Thanks.

 

[hans007]

4 pin power connectors are for pwmm.

3 pin connector is, rpm sensor, power ground.

4pin is those 3 plus another wire that i is for speed control. i am not sure exactly how it works, but it is supposed to pulse current or something.

unless you are talking about the 4 pin molex like older hard drives and current cdroms. those connectors have a 12v power and 5v power and ground for each.

 

[NoobyDoo]

Thanks.

I was referring to the connectors on mobos for the CPU cooler fan. So, with a 3-pin fan you cannot control speed ? That is, the fan will always run at a fixed speed ? Getting a bit confused actually.

 

[hans007]

Originally posted by: NoobyDoo
Thanks.

I was referring to the connectors on mobos for the CPU cooler fan. So, with a 3-pin fan you cannot control speed ? That is, the fan will always run at a fixed speed ? Getting a bit confused actually.

some motherboards will lower the voltage on the power wire based on some temp sensor on theboard. like i think asus has something called q-fan or something, but most motherboards do not have fan speed control on a 3pin.

 

[NoobyDoo]

OK. So if you have a mobo with a 4-pin connector ( and PWM ), you are better off using a fan with a 4-pin connector. That right ?

 

[NickelPlate]

The difference between 4 pin and 3 pin connectors is about 1 pin. Hardee har har, sorry couldn't resist. :laugh:

But seriously, 3 pin fans can still be speed controlled if the motherboard supports it. My old Asus P5GD2 premium had a DC option for 3 wire fans and PWM for 4 wire. My P5B is 4 wire only so a 3 wire fan will just run at max rpm all the time. If you've got a 4 pin MB connector it's probably best to use 4 pin fans but check your BIOS for other options.

NP

 

[Sjokoprins]

Hello!

I dont know what the 4-pin stuff does but i have a 3-pin motherboard connector which can lower the voltage to the fan. The other 2 connectors do not have this. Via speedfan (free program) u can manage the fan's speed. In speedfan prog i usually set the speed between 48% and 100%. At lowest temperature it stays at 48% (688 rpm). Below 48% the fan shuts down completely.
Keep in mind that the fan itself is capable of powermanagement support