Fan control on H170M Pro4

Hi again. Isn't this an official Asrock support forum? Why do I get no answer for several days?

Hi, I just opened new thread with my H170m-itx. 

frankvw wrote: I'd be interested in the answer for this too.  Just built a new PC for a friend with the H170M-Pro4 mainboard and put in an i5-6500 CPU.  The stock CPU fan ran at near 1900 RPM between 50-100% PWM and stopped completely below 50%.  I suspected a faulty cooler.  Replaced the cooler with one from an i5-4590 that I had laying around and I can now adjust fan speeds between 800 and 1900 RPM with 40% to 100% PWM respectively.   I was looking for information on the PWM_CFG1 header when I found this post.

The issue of faulty fan speed control with one version of the Intel stock CPU cooler supplied with Skylake processors has been recognized by ASRock recently.

Your experience using an Intel stock CPU cooler from a Haswell processor (it works fine) confirms that the Intel CPU cooler supplied with your friend's i5-6400 processor should be the version known to have this problem. That is, the label on the cooler's fan will have NIDEC printed on it, the manufacture of the fan.

I don't know if Intel has said anything about this situation, and I have not checked Intel's support forum for questions and answers about it. In theory it is possible that the PWM control on this particular fan has been changed so much relative to previous fans for some reason that it would cause the CPU fan speed control on our Skylake boards to require a modification. I imagine that something that basic and significant would have been communicated to mother board manufactures by Intel, IF it was true.

PWM fan speed control is a well defined specification, that must be used by any manufacture of PWM fans. Any change like that would affect every existing PWM fan in use in PCs. They would no longer operate as they originally did if a major change to PWM fan speed control happened. That's why IMO these NIDEC fans must be defective in some way.

The H170M Pro4 and most if not all ASRock Intel 100 series chipset boards (Skylake boards) have a UEFI/BIOS update that includes in its Description, "Modify Fan Behavior", or "Improve Fan Compatibility". These UEFI updates include a fix for the stock Skylake CPU coolers using a NIDEC PWM fan.

My Z170 Extreme7+ board has an update with this change (3.00), which adds an option in the H/W Monitoring screen, where the fan speed control options are located.

The new option is CPU Fan Type Setting. It has two settings, Auto and "4 Pin". This option may have a different name in another board's UEFI. The description for this option in the UEFI is:

If using NIDEC made retail cooler, please choose "4 Pin" option.

IMO, the use of "4 Pin" as the setting name is confusing. If you don't read the description, it implies (in my mind) that you should select 4 Pin with any PWM fan connected to the CPU_FAN1 connector. That is not true. Auto should be used with ALL PWM fans, except the NIDEC made Skylake stock CPU cooler. Setting it to 4 Pin on my board caused a Cryorig QF120 Performance PWM fan to run at full speed, when I had a Custom fan speed profile in use.

I see the PWM_CFG1 header on the H170M Pro4 board too. It's at the top of the board, just to the left of the CPU_FAN1 connector. It is not described in the board's manual, or shown in the Mother Board Layout diagram.

I have no idea what this header's purpose is. It looks like a two pin header that a jumper like the one used on the CMOS Clear header would fit on. I would NOT suggest doing anything with it until we know what its purpose is.