CPU fan running at full blast, even when the CPU is cool.

[TheGuardianWolf]

This is my first build. I thought something unexpected might happen, but nothing like this...

I have an ASUS M5A97 LE R2.0 motherboard, and a Athlon II X4 620 CPU, with the stock 3-pin CPU heatsink fan. The problem is that the CPU fan is constantly running at 100%, over 4k RPM and it's loud. It doesn't seem to matter what I do in BIOS or otherwise, I've tried messing with fan temp settings, and Quiet 'n' cool, but it's always going full blast. The CPU is only running between 20 and 30 degrees Celsius, and I've set the perimeters to run low when below 40, just to make sure I was well within the limit.

So I tried running a separate program to change fan speeds, but it also did nothing to the CPU fan, and additionally controls all 3 of my case fans at once with only one of the power settings. So I then tried connecting the CPU fan to the case fan slot, and it indeed was able to be manipulated that way, along with the other two case fans plugged in, so I don't think it's the fan or the wires.

My last resort was downloading the add-on tools provided by ASUS, but even that proved no luck. Note the right side of this screenshot. Even at supposedly 0 volts, it's running strong.

http://i.imgur.com/qGKQP72.png

From the information I've looked up, it seems like some motherboards can't control 3 pin fans? This doesn't make much sense to me, since the fan is obviously able to be controlled by voltage. I can even do so on this same motherboard by switching it to a 'case fan' slot and messing with the power level manually. But in the CPU fan slot it's always going 100%.

So I guess my first question is, do I need a 4-pin fan with this motherboard to have the fan running at different speeds? If not, what am I missing here? Did I do something wrong, or is there a problem with the motherboard? If there is a problem with the motherboard will a 4-pin fan fix it regardless?

Either way, will it hurt anything for it to run 100%? At least until I can do something about it?

I'm really hoping there's something inexpensive I can do, because it's LOUD, but I really don't want to have to return the motherboard. I've been without a PC for weeks, and finally got my very first build together... I really don't want to have to undo that hard work now!

Thanks in advance for any assistance!

 

[Deuce65]

There are two primary ways motherboards control fan speed. PWM, and voltage. With PWM, the motherboard sends the full 12 volts to the fan on pins 1 and 2, and uses pin 4 to control the speed with a PWM signal. With voltage control, the motherboard sends a variable voltage to the fans on pins 1 and 2, and pin 4 (if present) is not used at all.
Asus motherboards have PWM control on the fan headers labeled CPU_FAN, and use voltage control on the fan headers labeled SYS_FAN. So in this case, your motherboard actually IS controlling the speed of the fan just as it is supposed to, by sending a full 12 volts to the fan and then sending a PWM signal telling it to run at some lesser speed. But since your fan is not PWM, it doesn't get the "slow down" signal. For the CPU_FAN, there is no good way around this, just get a real PWM fan.

 

[cdrkf]

There are two primary ways motherboards control fan speed. PWM, and voltage. With PWM, the motherboard sends the full 12 volts to the fan on pins 1 and 2, and uses pin 4 to control the speed with a PWM signal. With voltage control, the motherboard sends a variable voltage to the fans on pins 1 and 2, and pin 4 (if present) is not used at all.
Asus motherboards have PWM control on the fan headers labeled CPU_FAN, and use voltage control on the fan headers labeled SYS_FAN. So in this case, your motherboard actually IS controlling the speed of the fan just as it is supposed to, by sending a full 12 volts to the fan and then sending a PWM signal telling it to run at some lesser speed. But since your fan is not PWM, it doesn't get the "slow down" signal. For the CPU_FAN, there is no good way around this, just get a real PWM fan.

+1 to the above. I think your best bet is to buy an after market cooler with a 4 pin fan. It won't cost alot for example:
http://www.ebuyer.com/500936-gelid-gel-slim-silence-aplus-cooling-fan-gel-slim-silence-apl

 

[jaimelmiel]

some Mobos such as biostar can be set to 3 pin or 4pin Pwm. The stock cpu heatsink fan for your athalon should be a 4 pin Fan. A good cheap and better Than syock spu cooler is the coolermaster hyper 212 EVO. It has a 4pin heatsink Fan. and is 120mm x 25 mm. And no it woill not hurt to run it at full speed

 

[Deuce65]

ASUS boards do in fact have this option. This doesn't turn the non PWM fan into PWM though, it simply tells the board that there is a non PWM fan connected and so use voltage control instead of PWM control. If OP is looking for PWM control this will not help anything. If he just wants the fan to run slower, than this would do that.