AGP and AGP pro

Standard AGP cards will fit in pro slots, but not vice versa. Funny thing though AFAIk there are no yet ANY AGP pro cards available. The spec has been around for more than a year, too. There may be a few high end CAD cards using the PRO spec, but I'm not sure. As for what the differences do, I have no idea. Although I think a few of the extra pins carry much needed voltage to our already undercurrented (Is that a word?) cards.