Wow. Thanks everyone for responses so far. It's super late here, so I'll read the whole thing carefully tomorrow morning!

THANKS AGAIN!

 

I know of 2 people who have used Noise Foam and it worked ridiculously good,

but how noise-free do you want it? I really can't tell my pc is on or of and it is literally 50 cm away from my ears.
I use: 2 front cage fans one in back-top 1 in the back, 1 on my cpu. these are all 120 mm,

all these fans run at their lowest speed, the wind is always cool. only thing bad about this is all the dust it collects

 

Kwissbeats, would you be able to find out from the people you know if their machines get hot or not? Also how many fans. I am between foam or liquid cooling...

I don't mind if the computer is absolutely quiet and completely noise-free. I always know when it's on

 

Making a noiseless PC is easy. Big cooler, a big fan on minimum RPMs on it, fanless PSU, SSD drive. COOLING the thing is a whole other story. :-(

 

The best solution for me was to place the PC in another room.
A hole on the wall for keyboard, mouse, audio interface, monitor, usb hub, and You can mount even an additional 220 V. fan if You want...
The silence is total!

 

That's an interesting PC there. I don't really have any experience with customized computers. A good friend built mine with mostly spare parts (pretty good ones though). But what's the deal with the fan outside the case? Obviously there's some cooling advantage or it wouldn't be that way, right?