Killing some noise in my equipment. While Noctua fans are overpriced and always have had a ... unique ... color scheme.. They sure do run quiet and move a lot of air while doing so.
Post-op report:
Well, the new 80mm fan perfectly in my HP 54600B. It moves more air, while being so quiet I literally can't hear it. With the original fan, the HP was one of the loudest things in my room...
But not THE loudest. That prize goes to my Tektronix PS280 power supply. This thing sounds like a 747. It uses a 60x60x20mm fan. I replaced it with a 60x60x25mm fan, and it does fit, if you remove the mounting bracket, and flip it around, giving you exactly 5mm more room, which is needed since the original fan sits flush against the outside case.
Also needed to trim down the bracket mounting screws... No problem there.
Old fan was hard-wired into the PCB. So I cut the original wires at the fan, tinned, attached a 2 wide header, tidied it up, and bam, pluggable fan header. New Noctua fan fit great.
Upgrade successful! I can now hear myself think with all these instruments turned on...