Motheboard Huananzhi - X99-TF short circuit on 12V line cpu. I found two died Xiamen RF 3NA7R2 . This transistor is not available for sale on aliexpress. Is there any replacement for him ???

Roughly - any mosfet from CPU VRM high side.

Accurate - any mosfet from CPU VRM high side with I_d 50+A and RDS_on less than 7 mOhm. Unfortunately I am not sure about gate capacitance, but seems that old good PH7030AL will be good replacement.

UPD: you can also look on SM4377NSKP, it is often installed on similar boards.