You need to know the amps still though, if you card is under powered then it will cause crashing and reduce teh performance of the card.
It will work, but you not see an increase of performance from 2gb to 3 as the PC will still use the page file for what isn't needed straight away, leaving just over 1gb never used unless you do what I did the other day and transfer a movie into its frames and import those frames into photoshop at the same time.
