I'm looking to buy a MP 2x QC Xeon 2.66 off ebay (which I'll later upgrade to 2x 3Ghz), plan on using it to crunch data (folding, BOINC-ing, you name it). I never owned a MP before but I do own a Xeon westmere workstation (2x 3.4ghz xeon x5690) which is VERY loud. I want to know how loud a Mac Pro is. From what I've seen it's using more passive cooling than active so I'm expecting less noise from it. My current workstation is housed in a supermicro server case with 6 redundant fans and is insanely loud.