So the 5406 is a great switch that can be had cheap on eBay if you keep an eye out. My current unit came with 2 blades and 2 power supplies for $200 shipped. The only problem is that now that my basement is finished and used, the noise which was ok for a datacenter, was too much for a homelab.
I solved this problem by ordering 6 Noctua fans.
4-NF-R8 Noctua’s for the power supplies (2 each)
2-NF-P12 Noctua’s for the fan card
WARNING – taking apart the high voltage powersupply is bad, mmmmkay? You could get shocked, killed, deaded, hurteded or blowned up (according to my youngest).
The power supplies are the hardest part of the project, requiring about 16 tiny screws to be removed. But once inside, remove the 8 exterior screws holding the existing fans, unplug the fan harness, and remove the fans. I cut and re soldered the stock connector onto my two fans, and re-assembled. No problems. The power supply fans are 2 pin, you’ll only connect black/red just like the factory wires.
The fan card was much easier. Use a screw driver to pry the 8 quick release pins out, swap in the new fans, solder the wires (I taped and shrink-tubed them) and re-attach using the Noctua low noise mounts. The Noctua’s I used for replacement here run at 1300rpm, the stock fans ran at 2300rpm. The HP does flash a fan error, however it runs cool and quiet. You can check by running “show system temp” at the command line. It will throw errors into the event log. If someone finds a quiet fan that runs at 2300rpms, let me know!
Put everything back together and viola, your HP is whisper quiet.