http://forum.mikrotik.com/t/adding-a-cooling-fan-to-crs326/138630/1
At the moment my CPU is at 69-70 degrees with an ambient temp of 21 degrees.
I’m planning to also install a fan in my CRS-326. Probably a Noctua FLX fan that I will reduce in speed by adding some resistors in series with the power supply.
I might even install a small switch on the front of the router to switch between high/low RPM’s.
While I’m at is I’ll also install an internal (12V/36W) power supply.
https://www.instructables.com/Mod-Internal-Powersupply-Into-Mikrotik-CSS326-24G-/
And some heatsinks on the SFP cages.
http://forum.mikrotik.com/t/sfp-module-is-extremely-hot/117746/1
This way I hopefully only need to open and service it just once in his lifetime..