Fan control is suppose to be really good on the Asus boards. The gigabyte fan control from bios is very basic. In mine (z170 gaming itx) it says something like this - 1.25pwm per degree C. And goes up in numbers like 1.25 then 1.50 etc etc. I read that Asus allows you to set a max and min fan speed based on rpm or %. Gigabyte doesn't.
Don't think the fan control on my GB X79 board even works at all heh (other than for the CPU fan and the first system fan) - I use an external fan controller anyhow so I can set them physically.