Handmade PC case sound dampening

[crislink]

Hi everyone.

I've got an HAF 922 case, never complained about it, but I want to make it quieter. The case is full of holes for ventilation and this is the main problem. I would like to keep the case since it's good for me and I want to spend 15 /20 euros instead of getting a new case (i would go for a Corsair 400q )
I've already disabled all of unnecessary fans and I'm not running hot (no stress usage or overclock).
I would go for an internal sound dampening solution, but I'm not certain wich dampening panel would be the best for this purpose:

- Silverstone sst-sf01 pads ( 0.4 cm thickness)
- flat foam panels 1 cm thickness
- pyramidal foam panels 3 cm thick

What do you suggest?

 

[Deleted member 184142]

What is making noise?

Most sound deadening is done at the very end as it's impact without having an almost totally sealed case is small. Most sound reduction is from picking correct slower speed fans and pumps etc and HDD isolation.

 

[crislink]

Well, I'd partially solved with a fan hub regulator. It's a little circuit board with 8 3pin inputs powered by a sata cable. It has a switch on top that has 3 positions LOW OFF HIGH. It's basically a voltage regulator (high is 12V) and low should be 7V i think. Bought it on amazon for 7 euros.
Of course I set it on low and the noise lowered at least by 50%. I think if I'll add a sound dampening foam inside the case it will do the rest.