They are solid machines (I have one). A few thoughts:
* Eight core is obviously better than 4, but I'd take a 4 core 4,1 over an 8 core 3,1.
* Make sure the DVD drive works (can read/burn), as these do go bad over time.
* Make sure all the fans spin at normal speeds (none are revving up all the time) and don't make any unusual noise (should be smooth, no rattling). That includes the graphics card.
* If you have the time, make sure that the drive can be booted from all 4 bays.
* Look out for excessive dust ("dust bunnies" clogging anything).
* Cosmetic deficiencies drastically reduces value. Original packaging tends to increase value a little, but don't pay more for it unless that's important to you.
Don't pay extra for useless frills. Like with cars, "upgrades" often don't add much value. Personally, a machine with a lot of extra spinning drives (as opposed to SSDs) is not interesting to me, at least if you are asked to pay for them. Used disk drives are basically worthless, and these days most people would want SSD's anyway (don't pay too much for those either!).
On the other hand, a good upgraded graphics card, especially an official Apple 5770, would be nice and is worth a few extra Euros. Extra memory is good and worth a little money too (but, again, not too much).
Good luck.
hello everyone,
i'm thinking of buying a 2008 mac pro second hand, and i wanted to know known faults etc. so i know what to watch out for when buying one.
thanks in advance