Few things you can do to quieten them. If there's a lot of whine, newer fans have quieter bearings, swap the fan out for a new one. Secondly a lot of the aero white noise is made by grilles and sharp edges being real close to the fan blades. You can reduce this a bit by stacking washers, rubber if you have them, between fan and mount holes, so it gets a bit of clearance. Alternatively, you can cut out the "punchout" grille entirely and replace it with a chrome wire one, which has less edges and also stands off a little further. Also fans are available with temp control built in, so can be whisper quiet while nothing much is going on then ramp up to full blast if the temperature climbs.

Ok thanks. I opened the PSU and it looks like the fan is wired directly to the circuit board (for power), so I don't think I'll go the route of buying a modern fan and swapping this one out. Do modern fans take 12 V like this one?

There's no space in the PSU case to mount the fan further away from the metal vents, though this sounds like an interesting fix.

Are there any modern, currently manufactured AT or ATX power supplies that I could swap the whole PSU out with?

Fans take 12v. I've swapped a Noctua fan into an old PSU by soldering half a fan extension cable to the wires coming out of the PCB, it was a huge difference, from continuous whirring sound to inaudible.

Replacing an old PSU is always a good idea, but modern PSUs don't have -5v and don't supply as much amps on the 5v rail. So whether one can be used really depends on the system you're using it with (is it a Pentium 3 or an Athlon XP...).

Evercase sell retro PSUs http://www.evercase.co.uk/index.php?route=pro … ategory&path=59

If you go high enough on the wattage, you can get something with high amperage on the 5v line.

That being said, it isn't going to matter a whole bunch since a system like that is not going to have a huge power draw anyway.

A new ATX power supply is going to be super quiet and put out immensely cleaner power and also be way less likely to fry your other hardware if it does die.

A Seasonic 450W meets the 5v 20A requirement that you are wanting:
https://seasonic.com/focus-gold

If you really need the -5v (very few things require this) then you can add that with an adapter or special expansion card.

I have a Seasonic S12III 550 W 80 PLUS Bronze with 20A on 5V. It is sorta cheap. Can't say if it is quiet. I haven't really thought about it.

Downside is that it has too few molex and a silly amount of those SATA power connectors.

I've change a lot of PSU fans out for qieter ones it really is what the solution is.

how about this?

400W

Neat, I have a project that would like one of those.