In message , Al Reynolds
writes
Morning,

I want to put my PC in a cupboard to reduce the sound
impact of the fans. Before anyone suggests that I get
quiter fans, please bear in mind that this is a very small
form factor PC and I haven't got the time to go finding
exact match parts that will fit in its tiny case!

These people are a good port of call for all manner of cooling and noise
suppression.

http://www.quietpc.com/uk/

Hth
Bill