I've had my Mac Pro 2008 for years, I bought it as a refurb from Apple in mid/late 2008. Its always worked without a hitch, besides the fans reving up unusually loud unless kept in relatively cool temperatures (The Mac Pro likes the room temp below 65F). Years ago I read that the Mac Pro regulated some of its fans by wattage load and not actual tempature on XLR8yourmac but I couldn't ever verify that. I've downloaded Macs Fan Control which allows you to config the fans manually and bypass the defaults and "safe", plus configure your own logic based on tempature ranges. I can't find operating safe averages, but having observed it (very unscientifically) I have a generally feel for what's normal (CPUs usually are 140F-ish, Northbridge/IOH 150F, RAM dimms about 120Fish, PSU 125F-ish) but I can't find any recommended ranges. Anyone know the safe operating ranges?