I was dealing with the same issue. I just got 4 S9's . 3 have the shit fan( not YLD12BM-12D)(just ordered 3 others from aliexpress https://www.aliexpress.com/item/Cooling-Fan-Replacement-D12BM-12D-4-pin-Connector-PWM-12038-12v-2-3A-6000RPM-For-Antminer/32850164857.html) and whine constantly. It is a piercing wail that gets in your brain and doesn't leave, building and building until you think your head will explode.

I found a solution. Reduce fan speed to 75% or somewhere in that range (3360/4920) current temps 82/74/76

Not to take credit for someone else's hard work ...

https://www.reddit.com/r/Bitcoin/comments/7hyaq7/adjust_fan_speed_antminer_s9/