Crosshair IV Formula OPT_FAN

[Mattiz]

Hi guys, nice forum, I'm new and I hope to have posted in the right section.

My problem is that I have a Crosshair IV Formula but I don't know how to control OPT_FAN 1/2/3. In BIOS there are two options "user mode" and "duty mode" I assume that duty mode just make the fan run at certain rpm not changing its speed when cpu runs hotter.
So I choose "user mode" setting lower temp and max temp, but my three PWM fan are running always at their lowest speed. I read of people having the same problem, more or less, and seems that max temp and lower temp are not referring to cpu temp but they refers to temperatures measured by OPT_TEMP 1/2/3 sensors.

So my question is, is it true? Do I have to buy those sensors in order to have my fan run at different rpm? And how and where they have to be installed?

Thank you all for the patience!

[Imperial_Guards]

You know, that explains why my OPT fans have had some issues. If no one gives you an answer, you could just switch them to a duty mode that is effective but not loud. I will say that I have some Noctua 140mm 3000rpm fans and "User mode" did not work well with them. Even duty mode under 50% would not let them spin.

I hope you get a solid answer! How fast can you make your fans go before they bother you?

[Mattiz]

The 1000rpm ones at 700-800, the 1200rpm at about 900.
I'm waiting since Monday, then I'll buy some sensor and give them a try

[noobOC]

Im sure OPT fan connectors are to be 3 pin fans. I still can't get fans to run 600rpm

[Mattiz]

noobOC wrote:
Im sure OPT fan connectors are to be 3 pin fans. I still can't get fans to run 600rpm

Sorry, didn't get your point. What do you mean? Mine OPT fan connectors are 4 pin and even if they are not "real pwm" connectors they have to work even with 4 pin fan

[Mattiz]

Ok, i bought those termic probe and they works great, the mobo now can actually control the three opt_fan. Everything is ok now