The 4224 case has stock fans, and I have the back fans unplugged, and the HD wall fans reduced to 5v instead of the 12v that they would normally be.  (your standard molex has 5v and 12v wires and I tapped into the 5v wire) System runs like a dream under normal circumstances with up to 10 3 tb drives, even during parity rebuilds temps stay in the 30's.  She is so quiet that you can hardly hear her and she pulls less than 50w at idle with all drives spun down.

 

However I have another 10 drives to load into her and now she warms up with the 20 drives especially during parity checks, punching through the 40's in the low 50's which is a little warm for my tastes.  However, most of the time the present cooling is sufficient, and when the drives spool down, there is no reason for the fans on the fanwall to run at all.  Changing the wiring of the 3 fans on the fanwall to 12v immediately pulls the HD temperatures back into the low 30's so present fans are all that is required.  I just need a way to have them automatically switch to 12v when temperatures hit 40C.

 

I am considering a simple thermostat that would switch between 5v and 12v.  Has anyone another idea?

 

(I know this topic has been discussed several years ago, but wanted to know the latest success with it.  )

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On v5 rc8a, I have a Norco 4224 i3 X9SCM-F-O, 1-MV8, 2-M1015 and Antec 620C power supply feeding 10 (now 20) 3tb drives

Could use a fan speed controller http://www.newegg.com/Controller-Panels/SubCategory/ID-11-11?Tpk=fan%20speed%20controller or if you have a Radio Shack nearby you can roll your own linear or switching controller using NTC thermistor for probably around $10-$15.  Search the web for NTC fan speed controller schematics.