Problem with CPU fan regulation on ASUS PRIME B760M-A WIFI D4

SkyTerran

SkyTerran

SkyTerran

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I'm helping my cousin upgrade his prebuilt PC. It came originally with a Gigabyte H610M S2H DDR4 motherboard, i7 12700K CPU, Intel Box cooler and 4x case fans making a ton of noise. I replaced the fans with what I had laying around - 2x Noctua NF-P12 (which have 3 pin connectors) and 1x Thermalright 140mm. The fan regulation on the Gigabyte motherboard worked perfectly out of the box. But as the VRM is quite weak and has no radiators I decided to change the motherboard and bought an ASUS PRIME B760M-A WIFI D4. Connected one of the Noctua fans and the Thermalright fan to the case fan connectors and those worked perfectly. But the last fan connected to the CPU fan header is a huge problem. No matter what I set in the BIOS (which is the latest beta version from two weeks ago) or in the Asus Fan Expert 2 application the fan works on full speed - around 1280RPM and makes a lot of noise. Even when the CPU is idle and has temperature 38C. I tried the Fan Control app from GitHub - it detects the two case fans, but not the CPU fan. In the BIOS for the two case fans I have a choice between PWM and DC regulation, but the CPU fan shows only Automatic.

In the end I connected a Noctua low noise adapter between the fan and the headers and now the fan is silent, but when the CPU is under load, the fan doesn't speed up - leading to throttling.

Any ideas how to fix this issue?
 
Check the manual for the motherboard, it may be that fan control is simply not possible on the CPU_FAN header. Just use a different header for the CPU fan, the motherboard will throw an error/warning that CPU_FAN is disconnected but you should be able to disable that.
 
Is this the Intel box cooler you are trying to control? If so that is not up to cooling a 12700K anyway which is why it doesn't come with one. You need a decent tower heatsink such as the Thermalright Phantom Spirit PS 120 or a AIO to keep that cpu under control.
 
Replaced the CPU fan with a Noctua NF-F12x25 PWM, which has a 4-pin connector and the issue disappeared. It looks like this motherboard has problems controlling fans with 3-pin connectors.
 
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