I had a quick look around at overclockers (UK) for some quieter fans to replace those on my Xserve's PSU. There is one fan at each end of it. I haven't measured them yet but they look like 40mm fans. They are however, double the depth of a standard 40mm GPU fan, though there is only one blade. The other 'half' has moulded blades which do not move.

These things are seriously noisy. Anyone who has ever heard a G4 Xserve running close up will know the noise I mean and these two little fans are almost entirely responsible for it. I want some quieter ones.

I only found one 400mm fan on overclockers:
(top one).

This is only single depth, is this likely to make much difference do we think?

The label on the stock fans reads as follows:

Magnetic Levitation System
DC12V 2.6W

Not that it tells us much.

Does the above YS Tech fan look like a good replacement? Anyone know another?