Fan controller RPM dip down and up in BIOS

[Droidene]

I have a question/issues about fan's speed.

At top i have a radiator with 3 fan connected to a ModMyToys 4-Pin PWM Power Distribution PCB - 4-Way Block (All 3 fan is also PWM)

When all 3 fan are connected to it, i get this in BIOS:


As you see, it dip down to zero and up all the time... whyy?


I tried to disconnect one fan and only let two fan running and it all fine, no dip down and up like this:


First i was thinking, oh wow.. that fan must be some wrong with it.. and swapped that with one of these two working.....same result.. it only dip down and up when all 3 is connected.

 

[Alaric]

Two fans have to run at an elevated constant state to maintain the temperature within pre set parameters. All three fans can drop the temp below the threshold, so the fans slow down until the temp rises again. Try setting a lower temp threshold and the fans should run at a steadier state..