I bought a 2006 Mac Pro off of eBay that functions fantastically, except that there's what sounds like a bad fan noise emanating from the rear exhaust fan - I took the side panel off and pin-pointed to where it was being produced (the noise). So I ordered a brand NEW Official Apple replacement memory cage with rear exhaust fan for $44 shipped. Now, how difficult is it to replace one of these? PowerBookMedic has kind of a incoherent, imprecise video of removing the internals of such a Mac Pro (1,1 2,1 3,1 2006-2008), and I think I got a general idea of how to do it. But has anyone ever done this before? Any tips? Besides being grounded, of course.