Intel Core i7 9700K - fans being weird?

[Tealx]

Within the past year or so I've noticed the CPU fan acting strangely. When it's idling the fan will go from 10% to 40% rapidly, and back down to around 10% again. I've checked the CPU temp using HWMonitor, and while there is some correlation the fans still get loud even if the CPU usage is very low.

I downloaded this program called FanControl to manually control the fan speed which works well. The CPU package temp can be around 40-50 C and when I disable FanControl the fan speed automatically goes up to what sounds like nearly full speed. Has anyone else had this issue and are there any solutions besides forcing the fan to be consistent while idling using FanControl? The temperatures are low, around 40 C but without FanControl it's like the fan doesn't know what speed it should be and it keeps going up and down. Hours after playing a game the fan speed will seem to stay stuck at whatever it was during the peak of a gaming session (even though the CPU has cooled down) and it'll stay like that indefinitely until I either restart or use FanControl to force it lower.

 

[Tetras]

Within the past year or so I've noticed the CPU fan acting strangely. When it's idling the fan will go from 10% to 40% rapidly, and back down to around 10% again. I've checked the CPU temp using HWMonitor, and while there is some correlation the fans still get loud even if the CPU usage is very low.

Usually the reason this happens is because the CPU is boosting to a high speed (e.g. max single core clock) due to a program with a lightly threaded usage profile, like a web browser.

When the boost happens, it reaches a high temp on a few cores due to the high volts. You can often change how the fan curve behaves in the BIOS, sometimes with an option called RAMP UP/RAMP DOWN to allow more time for the CPU to return to an idle state before the fan revs up.

If this only happened recently, is hard to say why. It could be software that puts your CPU in a generally higher state of load, which then triggers the more aggressive fan curve. It could be that you're using an app that is not hardware accelerated (e.g. with video), whereas it was previously, hence the CPU has a level of load that it never had before.

Alternatively, it could just be the higher ambient temps lately have meant you're hitting an annoying point on the fan curve more often.

Hours after playing a game the fan speed will seem to stay stuck at whatever it was during the peak of a gaming session (even though the CPU has cooled down) and it'll stay like that indefinitely until I either restart or use FanControl to force it lower.

Hmm, I assume this behaviour is also new?

Did you install anything recently? Like motherboard software to control the RGB? I've seen this happen with the graphics card fans occasionally, but not so common with a CPU. I'd also check that the CPU fan header is firmly seated.