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What does a MOBO need to be able to automatically control fan speed based on the temperature

Tags:
  • Motherboards
  • Temperature
  • Components
  • Fan Speed
Last response: in Motherboards
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August 26, 2014 3:48:46 PM

What does a MOBO need to be able to automatically control fan speed based on the temperature of the components?

Thank you for your answer!

More about : mobo automatically control fan speed based temperature

August 26, 2014 3:53:03 PM

That's something that the BIOS has to support, technically not the mobo. Most newer, if not all newer BIOS' will allow for that control.
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August 26, 2014 4:13:00 PM

but doesn't it have to have a certain kind of connector, like 3 pin or four pin or something?
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a b V Motherboard
August 26, 2014 4:27:28 PM

Yes, it does need to be a 4 pin connector, usually referred to as PWM.
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August 26, 2014 5:21:27 PM

James Mason said:
Yes, it does need to be a 4 pin connector, usually referred to as PWM.


Thanks for the reply!

Look at this: http://www.amazon.com/dp/B00K2RQAQY/?tag=pcpapi-20

I looked at the first picture and found some "ports". they were labeled "SYS_FAN1" SYS_FAN2" "SYS_FAN3" "CPU_FAN" and "CPU_OPT". Each of the ones I mentioned had 4 pins.

Does that mean this motherboard could do it?

Thanks again for the reply!
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a b V Motherboard
August 26, 2014 8:28:59 PM

Yes.

Most CPU fans on motherboards are 4 pin fans anyways.

They also sell 4 pin splitters if you still need more fan ports than your motherboard provides.
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a b V Motherboard
August 26, 2014 11:06:22 PM

Yes, that mobo supports voltage control of case fans connected to the chassis fan headers (SYS_FAN). You can use either 3pin non-PWM fans or 4pin PWM fans - either way, speed is regulated by voltage control based on your CPU temp and pre-programmed or user-programmed profiles set in your BIOS or using fan control software. Speed control on the CPU_FAN only works with PWM fans - if you hook up a 3pin CPU cooler fan to this header, it will run at 100% full time. The CPU_OPT works similar to the SYS_FAN headers in that you can use either type of fan and speed is controlled through voltage, but it's slaved to the CPU_FAN so it will mirror whatever duty cycle the CPU_FAN header is running at.

With modern mobos, to really tell what the CPU and chassis fan headers will do, you need to look at the header pinout in the manual. On the Gigabyte Z97X-SLI, all of the headers are 4pin, but the CPU_Fan is the only true PWM header. The rest of them use voltage control to manage fan speeds, regardless of whether the fan plugged in is 3 or 4 pin.
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August 27, 2014 12:28:27 PM

So what exactly is the difference between PWM and voltage control? Is PWM better?
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a b V Motherboard
August 27, 2014 1:04:51 PM

PWM fans on a PWM header receive a constant 12V. To adjust the speed of the fan, the mobo sends a pulse width modulation signal to the fan controller in the hub of the fan, which in switches the motor on and off very rapidly. The mobo (or fan control software by extension) can gauge the exact (or very close to exact) ratio of "on" time to "off" time needed to get the fan to rotate a designated speed. This allows a much finer degree of control than simple voltage adjustment. PWM fans can also idle at a lower speed than is possible with voltage control.

Voltage control works by raising and lowering the voltage applied to the fan. 12V applied results in the maximum speed capable. As the voltage is reduced, so is the speed of the fan. The mobo senses the speed via feedback from the tach wire (the third pin on a non-pwm fan), then adjusts the voltage as appropriate. There is more lag in control and more fluctuation in fan speed, since the voltage is constantly being adjusted to regulate the RPM.

If you're using a non-PWM header, usually it's better to use a non-PWM fan. A PWM fan will work on it, but unless it's a high-quality fan like a Noctua you may get clicks or motor whine. If you're using a PWM header, unless it's a dual function header like on some Asus boards, if you use a non-PWM fan it will only run at max speed, so a PWM fan is better.
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August 27, 2014 2:56:56 PM

So basically even though my fan headers are 4 pin they are not PWM so I should get a non PWM fan?
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a b V Motherboard
August 27, 2014 7:35:48 PM

If you've got the Gigabyte GA-Z97X-SLI, then the only PWM header is the CPU_FAN header. All of the others are voltage control. There are very few mobos out there that have more than one PWM header, and many of them don't have voltage control either.

What case do you have?
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August 27, 2014 10:20:58 PM

I have the NZXT phantom 530. It has a fan hub that plugs into the power supply and ( I think ) the motherboard somewhere. Do you think I could control the fans with a program like "SpeedFan" when they are connected to the fan hub?
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a b V Motherboard
August 28, 2014 7:43:19 AM

You'll have to check the hub to confirm this. It should have a 4pin Molex coming off it and connecting to your PSU for power. If there's another cable coming from it that has a regular fan connector on it (it may be currently connected to the case fan controller) you should be able to plug that into one of the mobo headers. Then you can control it via Speed Fan. Speed Fan can be finicky so you'll have to play around with settings if it doesn't detect it. Also, because they're all connected through the hub, Speed Fan or whatever software you use is only going to see it as one fan. If you want to control the fans individually, you'll need to skip the hub and connect directly to the mobo.

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August 28, 2014 12:14:49 PM

I looked at 2 threads

1: http://www.tomshardware.com/answers/id-2024335/nzxt-pha...
2: http://linustechtips.com/main/topic/85501-nzxt-phantom-...

They seem to be saying that the fan hub plugs into the power supply and the MOBO so it should work.

I have one more question though: I know that the MOBO knows the temperature of the CPU but what are the other component temperatures are monitored?

Thanks for doing all this. You really helped me a lot!
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a b V Motherboard
August 28, 2014 12:37:16 PM

Depends on the mobo, but it can report temps for pretty much any component that has temp reporting capability: HDD, SDD, DRAM, GPU, CPU, PCI expansion cards. Your best bet for figuring out all the ins-and-outs of temp monitoring is to go through your mobo monitoring tabs and see what's in there. Google or wikipedia anything that isn't obvious or can't be figured out from context.

Same thing goes for any monitoring software. All of them have different layouts and sometimes label things differently, with varying degrees of accuracy. The only real way to figure them out is to use them. Each of the major monitoring programs have tutorials available online.
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