I had other problems with it - on CHA_FAN1 and CPU_OPT i cannot set any RPM - even on 10% power it stays at full speed
Hi, I believe I can help with the stuck at 100% fan problem. I used Speedfan 4.51 configure> advanced> (IT8620E at $A30 on ISA) > PWM 2 mode > Software controlled
CPU_OPT should be PWM 1 & CHA_FAN1 should be PWM 3. I have not found any setting in Gigabyte's SIV to affect this change, but once changed, SIV works properly with either graph or fixed mode. Also I have all fans in the bios set to normal currently. Without this change my CPU and CPU_OPT were stuck at 100%.
Speedfan can also set the fan speed now. I haven't noted all the intricacies, but the last program you apply a change in sets the fan speed. Also there is a "temperature 1/2/3 offset" which may be able to adjust the temperature which fixed mode in SIV uses; although I have not tested it. The graph mode should work fine tbh.
I did find it very strange having a problem in 2015 with fan speed control, its been a feature of motherboards since my first Abit KR7A-133.
This is the post I found which gave me this solution:
http://linustechtips.com/main/topic/211111-how-to-slow-down-fan-speed/#entry2865450