have some option that come to my head this time and let see which one i will be successful.
Option 1: Buy a silent type Fan. The problem here is that - i cant find a fan that have the same rating of the original fan - 6000rpm/4pin pwm
Option 2: Put them into box. or Foam cooler.
Option 3: Mineral Oil
Option 4. Silent Server Cabinet - a bit expensive - but for sure this will do the Job
Option 5. Refrigerator (Cooler) not the one with freezer - this could be the substitute to the Server cabinet.
Option 6. Put them outside. - not really a good Idea
https://www.dohangout.com/forum/viewtopic.php?f=44&t=308 <<- I will keep all my updates here on my website