i cant hear my PSU at all. all i hear is the case fan and the occasional hard drive spin up when i'm using one of them after a sleep. i can also hear the fan on the GPU when i'm gaming.
but there's a specifically troubling whirl in yours that sounds like bad bearings.
Either way.. this Mac Pro will be gone by Monday / Tuesday (UPS are picking it up) and she put a new one on high priority and "Fast Ship EMEA", she said it should arrive within 1 week or so. I just hope Foxhound... eerrr.. Foxconn won't be rushed to assemble yet another faulty Mac Pro, otherwise I'll go Solid Snake on their asses