updated 12:55 am EST, Fri January 11, 2008
8800GT: not for 'old Pros'
Owners of the previous revision Mac Pros may be out of luck if they wish to upgrade to the new Nvidia 8800 GT card that is available to the new towers. Several threads in Apple's forums [1|2|3] indicate mixed impressions, even when users contacted Apple directly; the US representatives were adamant that the card would not function on an older Mac Pro, while Apple UK employees said the card would. Users have presented research that shows the cards should be backwards compatible, some are so confident in their beliefs that they ordered an upgrade kit without waiting for official confirmation.
Bare Feats owner Rob-ART mentions that he has spoken with both Apple about the issue, and they assured him that the card would not function due to a firmware incompatibility. Several Blizzard employees dismally confirmed those findings, since they were eager to upgrade their Mac Pros with the new graphics card.
The closest answer users can find is a vague statement in a support topic that mentions various cards from the power-user lineup, and notes "All of these cards are only compatible with the family of computers with which they shipped."
The previously mentioned upgrade kit does not list requirements on its product page in the online store, merely identifying it as "NVIDIA GeForce 8800 GT Graphics Upgrade Kit for Mac Pro". Many high-end users and gamers that have purchased the earlier model Mac Pro are upset about the lack of graphics card upgrades, expressing feelings of abandonment by Apple.