I usually would stick some sponges on casing as the sponges would absorb vibrations & noises which help somehow,
make sure the sponges weren't obstructing the casing ventilation.

I remember a short lived fad for that in the Athlon days. They used to sell a "noise reducing kit" for some stupid high price that was merely double-sided tape and some of that conical packing foam;

I never thought it was very effective to be honest and I never used it personally. Then again, I never really cared about the noise a machine made anyway, a lot of mine have been very loud because I go overkill on the cooling and generally take the jet engine racket as a sign it is probably working.

God there was some stupid crap around back then. Some of those kits had rubber grommets for fans, the PSU and anything else though could think of (I do have some of those). There were other kits which placed a fan sucking the heatsink (wrong way!) and connected a duct from there to the 80mm front case fan. There was a PSU silencer which was a box with a grommet which slid over the PSU, was filled with that egg-box foam like above and probably suffocated said PSU to death. I'd be surprised if any of these things worked. My Coolermaster case actually has that foam inside it as a factory feature and I don't see it helping any when I have a bunch of server-grade 120mm fans blasting air through radiators in there.

/rant over

Joey_sw wrote:

I usually would stick some sponges on casing as the sponges would absorb vibrations & noises which help somehow,
make sure the sponges weren't obstructing the casing ventilation.

Thank you, but I think that the 2 fans are about to die, the noise is really creepy (and high), I don't think that it is a matter of vibrations.
I see on Ebay a plethora of cheap chipset coolers, but I am afraid of buying something that could actually harm the mainboard.
Anyone tried something?

HighTreason wrote:

I remember a short lived fad for that in the Athlon days. They used to sell a "noise reducing kit" for some stupid high price th […]
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I remember a short lived fad for that in the Athlon days. They used to sell a "noise reducing kit" for some stupid high price that was merely double-sided tape and some of that conical packing foam;

[...] foam like above and probably suffocated said PSU to death. I'd be surprised if any of these things worked.
My Coolermaster case actually has that foam inside it as a factory feature and I don't see it helping any when I have a bunch of server-grade 120mm fans blasting air through radiators in there.

/rant over

Those were fake kits, proper one use sponges not foam. Foam were primarily designed as shock absorber and not as noise reducers.
But foam are cheaper and easier to accquires than sponges and so junks maker use that instead.

I've once experimented with cardboard to silence my 486 (ehh .....yeah I know 🤣!) and it actually worked a little bit! The difference was noticeable and it hasn't caught fire yet 😁

In theory bigger/better heatsinks with a case with better airflow will work just as well.
If you can get temp readings of the current setup, replace with some larger heatsinks and keep close eye on the temp readings.
Otherwise if the fans are a fairly standard size you'll probably be able to get quieter ones then the cheap stock fans here

The southbridge is going to be a difficult one if you intend to use Long Cards. As chinny22 said, a good passive heatsink with good airflow should do the trick.

Since I will connect SATA disks on the nVidia 2200 controller for better speed and lower cpu usage (learn that from a review) I think that I will put a tall but passive Zalman on it and a passive low profile copper heatsink on the southbridge to prevent obstructions with VGA.

What do you think?

Update...

It appears that the nForce 2200 chip is the side one, bad news...
I need to find something robust to cool this because it can reach pretty high temps under overclock.

Maybe an HR-05 SLI if I can find one for cheap.

Found for cheap (10€) this heatsink (coolink Chipchilla):

I will try to use it in passive mode, it shuld do, plus I hope the VGA will have proper space.

For the nVidia 2050 chip I will use a passive Zalman I found on my closet.