I've been the proud owner of a reasonably equipped Mac Pro since November (12 core, 2.66 GHz, 24 Gb, raid, 4x1Tb, ATI 5870). Always a bit noisy, but not excessively: a bit louder than a PC desktop, much quieter than a comparable workstation. A couple of reboots since then for SW upgrade, nothing changed. Last week I've put the machine to sleep for a couple of hours, for an electrical upgrade in the building (that never happened, but in any case there's an ups here). At startup it became DEAD SILENT, and has remained like that ever since. I really mean there's no noise coming from the fans (I always think this thing is turned off when I arrived, never in years of having PCs I've had such a quiet office). I did check the fans are alive: there's air flowing through the case, and iStat Pro reports normal temperatures and (normal?) fan speeds: from 600 rpm for INTAKE and EXHAUST to 900-1100 for POWER SUPPLY and BOOSTA and BOOSTB and 1500 for PCI. I've heard people complain about the noise of Mac Pros before, but I din't think I had a problem for the last 3 months. But I now wonder if I had a problem then of if I have one now... Could anything have changed so pronouncedly just from putting this to sleep? The process load is similar to before... Thanks for any comment.