[Gooserider]

You might try Silent PC Review (SPCR.com) for sound reduction advice - I look at them as the silence experts just as ProCooling are the cooling experts. Their standard is that computers should not be heard - period. Alot of the noise reduction stuff that I've mentioned comes from them.

I would repeat my earlier suggestion of sound dampening material, NOT sound absorbtion! The lowest cost stuff that I've found which works very well is available from good hardware / home improvement stores like Lowes or Home Depot, it's called "Roofers Tape", and is essentially a thick layer of rubbery asphalt adhesive with a thin layer of aluminum over it. Total thickness is around 40 mills (.o4") It KILLS resonance. It's about $15 for a 6" X25' roll, more than enough to do a case. Just cut it to fit with a utility knife, peel off the backing and stick it on. strips can be overlapped or run next to each other, and it isn't neccesary to cover all of a panel. The only downside is that it's a fairly irreversible process, once the stuff has had a chance to bond, it is NOT going to come off without a major battle.

Note that the tape has to go on the metal, underneath any other sound absorbing foam...

I did a bit of experimenting when I was treating my case panels - I hung the panel on a peice of wire and whacked it with a screwdriver handle to see what kind of noise it made. Before treating, it made a pretty decent gong, and would ring for about 10 seconds. After treating, it just gave a dull 'thud' about like hitting a plastic trash can - absolutely no resonance.

To reduce noise transfer between metal parts, I would use the earlier suggestion of putting foam weatherstripping tape between parts that are designed to come apart.

For parts that are permanently assembled (riveted), I would get one of the "GOOP" products, or possibly silicone RTV sealant, and run a bead down each joint, working it into the joint as much as possible. This should reduce rattling and do some damping.

Another thing I've seen done is to use bungie cord or other heavy duty elastic to suspend the pump in space so that it can vibrate without transfering any vibrations to other metal. This is more common with hard drives, but I've seen it done with pumps as well.

Hope this helps,

Gooserider