i have a hyper 212 evo on my cpu, i just currently installed a coolermaster 120mm fan to the back of the case, after turning on my pc, my cpu fan keeps dropping from 1000 rpm to 50>40> and eventually zero on idle, temp usually runs 15-23C idle.
So i'm assuming the fan stops completely? Or is it just indicating 0rpm but the fan still spins. Download software called "speedfan" it can control the voltages of exterior fans. I use it to control 6 different led fans on my case. You can control RPM as well. It's obviously set to auto.
fan doesnt stop, im assuming the censor is reading it wrong, since i have speed fan and hwmonitor, both show the fan going 1000+ rpm for a few minutes then randomly drops to 0 rpm for 1-2 seconds then goes back up.
Yeah just an off sensor or a miscommunication in the software. Nothing to worry about, happens all the time with certain programs. As long as it's spinning at a visibly high rate, it's doing exactly what it needs to. I have 2 Cooler master 120mms on my case myself and they do wonders for motherboard and CPU heat.