I want to change power supply fan in my Mac Pro 5.1
But unfortunately it is difficult to find this part in our country. What alternative fan can i use?
Mac Pro, OS X Mountain Lion (10.8.4)
The fans used inside the power supply will be commodity fans with the manufacturers' labels still on them.
Read the label on the existing fan. Look that exact fan up on the Internet to get the rating in cfm (Cubic Feet of air moved per Minute) and Sound rating in dB. For reference, 30dB is a typical office sound level, over 90 dB is a chainsaw.
The exact fans used are typically only available in the handy million-pack.
Find a 12Volt fan that is the correct size, has the same or higher cfm, and generates the same or less sound level.
This site sells a lot of different fans fairly cheaply: