A quieter case for the server
The server sits in a hallway cupboard, and for years it made a constant low hum that you could hear from the bedroom at night. The case was a cheap one with two small 80 mm fans that had to spin quickly to move enough air past the drives.
I replaced it with a mid-sized case that has sound-dampening foam on the side walls and room for two 140 mm fans at the front and one at the back. Moving everything over took an afternoon, mostly because I took the opportunity to redo the cabling properly and label every drive by its serial number.
The fans are now controlled by the motherboard based on drive temperature rather than CPU temperature, since the drives are what actually need the airflow. At idle they spin at around 500 RPM and are effectively silent behind a closed cupboard door.
The nice surprise was that the drives now run about four degrees cooler than before, which shows up clearly in the Grafana history. The total cost was less than a single new drive, and it is easily the most noticeable improvement I have made all year.