Updating the BIOS - Completely wipes out ANY prior settings, and MOBO Utilities can easily get corrupted with the BIOS updating.
BIOS:
Load Optimized ; page 50
{Fan ; page 45}
CPU Warning Temperature -> 60C/140F
CPU/SYSTEM/POWER FAN Fail Warning -> Enabled
CPU Smart FAN Control -> Enabled
CPU Smart FAN Mode -> Auto
"Note: The Voltage mode can be set for a 3-pin CPU fan or a 4-pin CPU fan. However, for a 4-pin CPU fan that is not designed following Intel PWM fan specifications, selecting PWM mode may not effectively reduce the fan speed."
If you installed ANY Gigabyte utility then uninstall it, utilities like EasyTune 5 cause more problems than they solve.
Failure:
Clear CMOS ; page 29
Repeat above
Failure:
Windows: run MSCONFIG, select - Diagnostic and RESTART
{If this fixes the problem then you have a BIOS invasive App e.g. EasyTune 5 or others messing with BIOS and your FAN(s).