joseph0510 :
ImPain :
Yes you can, they have to be the same chip so in your case 3x 560 so it is fine.
However, if they have different clock speeds, they will adjust to the lower one if I am not wrong.
Even if it adjusts to the lower one, they will give much higher performance than only one of them, right?
Yes they will give higher performances, how much will depend on the software/game.
Sometimes they take a huge performance boost from cards in SLI, but sometimes not.