Last summer in the UK was particularly hot and so I've been getting Ultron ready for the 2021 impending inferno!
Ultron resides in the attic along with the 48 port 1Gbe switch POE switch and the NAS machines. While the dual Xeons max out about 65 degrees celsius even during the hottest day, the hard disks were reaching 40˚ C!
I decided to purchase myself a set of Corsair AF140 dual pack of fans both red and blue. Red for exhaust fans with blue indicating intake fans (hot and cold). It just makes things easy from a visual point of view. The option existed to buy some RGB versions however there's no easy way of controlling these in unRAID. On that point they currently run at full speed as I've yet to find a way for controlling the frequency output reliably.
Disks now at 23˚ under full load! I would expect this will increase by maybe 5˚ - 10˚ during the next heatwave but no where near as bad as 40˚