No Arctic Cooling A30 CPU fan speed control from FM2A75 Pro4-M

[Bill McLean]

The H/W monitor in the UEFI setup shows the CPU Fan 1 (4 pin connector) speed as fluctuating between 1130 and 1160 RPM, with the CPU temperature 39 degrees. Changing the fan setting from 'Full on' to 'Automatic mode, level 1, target CPU temperature 50 degrees' seems to make no difference to the speed. After logging on to Win8 and waiting for the CPU to throttle back from 3.8GHz to 1.4GHz, the AXTU reports the CPU temperature at 30 degrees and the CPU Fan speed as 1125 RPM. The AXTU fan controls seem to have no effect on the speed. The Arctic Cooling Freezer A30 CPU fan is supposed to operate from 400 to 1350 RPM and I want to get the speed lower to reduce noise.

[parsec]

You are not the first person to have this issue. I have never been able to get the CPU Fan 1 speed with a PWM fan below ~1100 RPM. I've used fans rated at 500 - 2000 RPM, with the same result. It seems that the lowest speed a PWM fan is allowed to run at on the CPU Fan 1 header is ~1000 RPM.

A different board manufactures fan speed control software I've used has a calibrate feature for the PWM fan header. It checks the fan's speed with different voltages, and uses that information to set the fan speed. A line graph profile is used to define fan speed in % versus CPU temperature. But this method is not fool proof if the fan is changed and not calibrated. The board also has low fan speed warnings, which covers that problem.

I doubt there is anything you can do about this. Using the chassis fan headers with manual control, I have gotten fans down to ~500 RPM. Manual CPU fan speed control is ridiculous, so not a solution. Changing fans won't help either, unless you can find a 120mm fan that is very quiet at 1000 RPM, when mounted to your cooler.

[parsec]

UPDATE: I just noticed in the BIOS/UEFI for my board that in the CPU Fan speed configuration, in the fan speed level option, a new entry, Custom fan speed. That seems to have appeared with a new BIOS update for my board, whether or not your board has this option, who knows.

I will try it out now and see what happens...

UPDATE Update: Yes, this new setting lets you set the lowest CPU PWM fan speed much lower than the apparent default value of 1000 - 1100 RPM, when CPU Fan Speed is set to Automatic.

ASRock, thanks for this option! But I must comment on it from the view of the user.

The option is: Custom Fan Speed, that has one data field with valid values of 1 - 256, the higher the value, the faster the fan speed, which is all the help text states.

Sorry, but the name is vague. Is it the lowest, highest, or a constant speed? It seems to be the lowest CPU fan speed, but I had to try it to see what it does.

IMO, the range of values, 1 - 256 is good, a large range for adjustment to accommodate many different fans. Some people will not like using the numbers, and would prefer say 10%, 15%,... 100% for example. That really is not any better in reality, but would be more comfortable for some people. I hope you don't change it.

[Bill McLean]

Thanks for your response parsec. I tried the custom fan speed option with the lowest value 1, but the fan speed did not change: still between 1000 and 1100 RPM. I am wondering if the Arctic Cooling fan's PWM speed control is faulty; maybe I would have more luck with another fan.

[parsec]

Really, that is a shame. I'm using a Scythe 120mm PWM fan, rated for 500 - 1900 RPM. Setting the Custom Fan Speed to 60, with the PC at idle the speed is under 600 RPM. So this setting works fine with that fan.

The AXTU utility will override the settings in the UEFI, which I think happens even if you are not running it. Or it does if you run it at least once, and then close it (in this case a reboot clears AXTU's fan control.) Since AXTU does not have the Custom setting, we can't change that. I don't have AXTU installed now, so I am not sure what if any interaction between this setting and AXTU actually is. But it would not surprise me if it did override the Custom setting. IMO it's worth it to test this, uninstall AXTU and see if that allows you to lower the fan speed. Or at least do not check the Auto Run option of AXTU (if you do that now) and don't run it, and check the fan speed with another program.

It's also possible that your fan is so sensitive or efficient, that it can't be controlled appropriately by your boards PWM interface. I found a spec for the fan that rated the voltage range as 3.5V - 12V. That is one of the lowest fan starting voltages I've seen. But I would still do the test by removing AXTU.

[Bill McLean]

In fact I was thinking about a Scythe fan as a possible replacement. I do not have AXTU set to start automatically, but I will try uninstalling it to see if this makes a difference.

[Bill McLean]

Uninstalling AXTU did not help. In fact, setting the custom speed to 1 (lowest possible) caused the CPU fan to speed up to 1300 rpm.