With fans on full blast continuously, temperamental start-ups & differing RAM configurations, I eventually took it into an Apple Store. Now for the bad news: Service technician reported that "I have diagnosed the machine all these components has corrosion on it the Motherboard, one Memory Rizer board and the Heatsinks. I have send you the quote as well if we want to go ahead but I advise to replace the machine there is too much damage. That is why the fans are going crazy." Quote comes to half the price of a new Mac Pro. (And it's not a good time to buy a new one.) Seems a shame that all that great design, engineering and materials will probably be reincarnated as Coke cans. At least, I thought one should get more than 4 years of life out of it. (Living on the coast has its disadvantages, it would appear.) Very little to salvage (apart from data) But what to do with it?