i have the same quetion, even i from china
as i know this model zx h81 motherbord a lot made in china
i still cant F**K find way fix this problem, thats so noisy!
they most form by company 科脑(koloe) n 华南金牌(idn this company eng name)
i useed koloe zx h81 v3.1,the aida64 appear that use chipest z97

wish that message can help u
btw final i use 3pin fan solve...