Question fan connected to CPU_OPT seems to never turn on

Aug 13, 2019

Lately I finally added fans to my case and learned how ASUS's mobo software works. I used this Fan Expert thing they have which is essentially the only way to control fans speeds, at least in my case without this program fans were running at 100% all the time

Anyway, when you run this you can click "fan tuning" which detects fans and sets their speeds appropriate to temperature

Now, because I have H97 Pro Gamer MB i don't have a lot of headers to connect fans to, therefore I connected fan exactly above radiator to CPU_OPT as it made a lot of sense to me if I had to plug one fan into CPU_OPT anyway, because of lack of headers obviously

What bothers me is that this(4 pin) fan above radiator never works. It literally only runs for few seconds when I turn my PC on, even when CPU hits something around 76 degrees it still stays turned off while all other fans are working just fine

Any idea why?

Edit: what also makes me wonder is fact that HWMonitor calls CPU_OPT fan as Chassis #5, all case fans are called Chassis #1,2,3 and there's one called CPU and it's obvious which one it is. But why is the last header I could possibly use named #5, not CPU_OPT or at least #4
Last edited: