I'm running an always-on server with an AMD 8600G and an ASRock B650M-HDV/M.2, and I'm trying to reduce idle power as much as possible. After undervolting the SoC and adjusting the PBO curve, system power at the wall is around 35–42W, and I'm still testing lower voltages.
I'd like the CPU fan to stop completely while temperatures stay below 60°C, then start once the temperature rises above that point. I configured a custom curve with 0% fan speed at 60°C and 50% at 70°C, but the fan still runs at roughly 900 RPM even when the CPU is only around 50°C.
I'm planning to check the fan-tuning and zero-RPM options, but I'm wondering whether this motherboard actually supports stopping the CPU fan completely. I can stop a case fan when CPU temperatures are below 70°C, so I may connect the CPU cooler to that header instead.
The cooler is currently the stock Wraith Stealth, though I also have a Thermalright Full Copper AXP90-X53, which should handle passive or semi-passive operation better.
3 Answers
It may be possible if the BIOS has an option such as “Zero Fan Speed” or “Fan Stop.” Check whether the CPU header supports a true 0% setting, and try calibrating the fan first. Some headers won’t actually stop the fan even when the curve is set to 0%.
A very low constant speed may work better than repeatedly stopping and starting the fan. Once the fan stops, the heatsink can warm up quickly and trigger the fan again, creating a start-stop cycle that adds unnecessary bearing wear. Running a compatible fan around 300–600 RPM would still be quiet and use very little power.
You can try another fan header, such as the second case-fan output, if that header is known to support 0 RPM. Just make sure it still responds to CPU temperature and that the system has appropriate over-temperature protection.
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