Use a better CPU cooler and stuff a new, quiet 80 or 90mm fan. Measure first.

Another way to keep it quiet is to keep it off 😜

I found the stock Intel HSFs of that era to be too loud for my tastes. Best is to replace it with some retail CPU HSF that has better cooling and acoustics properties.
Also it may help to use an ATX case that is easier to cool, preferably with something like at least a 12cm exhaust fan and having the back part of the case (the part with all the tiny holes or the honeycomb part) removed with a hacksaw or something (do sand the sharp edges!). Having a PSU with 12cm fan will also help a bit here.
Resonating parts in the case also cause sound pollution and the harddrive may also contribute to excess sound.

There are lots of ways to quit down a rig, but the best way to remove excess sound is by preventing it altogether 😀

What I usually do is attach the positive lead of the fan to 12v and the negative lead to 5v so the fan runs with 7v. This will spin the fan fast enough to cool... usually 5v is too little.. but it cuts the speed down a lot so it's quiet. I recommend using thin wire to connect the 3 pin fan connector to one of the connectors on the power supply so that you don't have destroy anything by cutting/stripping wires. I've been doing this for years with CPU and case fans to keep the noise down as long as the systems stay cool enough to be safe.

Try that and keep an eye on things under load or buy a better cooler for it.

Find a Zalaman CNPS 7000 or a thermalright xp-90, there are other coolers but they are not as common. The Intel stock coolers have always been regarded as trash because they get too hot and the fan noise annoys most people.

Heatpipe cooler with a 120mm fan.

The Dell desktop computers of the P-IV era were nice and quiet due to them using a very nice for the time heatpipe cooler and a variable speed temperature sensing fan.

The stock Intel coolers have been absolute trash since the P-IV era. The only cure it to replace it with something better.

cyclone3d wrote:

Heatpipe cooler with a 120mm fan.

The problem is that there don't seem to be many if any aftermarket S478 coolers available to buy new or second hand (ebay UK); I have a couple of 120mm vertical coolers available but they're all S775 and beyond. So I might have to make my own way to mount one...

Zalmann made good aftermarket 478 coolers. I used to own own a couple years back.

Hm watercooling..
or fill the case with concrete, put it on the sidewalk and watch some funny things 😀

Research the good coolers from the era and keep a look out on ebay or Amazon, I've got old coolers from both.
I cant remember my shortlist now, but after a few months got a brand new Scythe Mugen 2 RevB 2 years ago.

use thermo glue and stick a water cooler straight to that cpu and overclock the piss out of it, my 3.4ghz p4 is at 3.9GHz stable with really cool temps at max load.

This one is quite nice and quiet:
http://www.ebay.com/itm/Scythe-SCNJ-2000-Ninj … n-/162607333500

http://www.silentpcreview.com/article893-page1.html

And if you could find that socket478 mounting piece* separately, I'm convinced you could make even Ninja 3 or 4 fit, which are much easier to find than the Ninja 2...
(*: check picture on box in the ebay link)

OR, perhaps this one below (me not tested), as at least it is available in the UK, AND without the silly shipping costs from the US....
http://www.ebay.co.uk/itm/Zalman-Ultra-Quiet- … w-/162585874864