I just bought a GIGABYTE GeForce GTX 770 GV-N770OC 4Gb card to upgrade from a old GTX 470. I found a deal and it cost the same as a decent 2Gb version. My question is; if I want to SLI this card in the future would I: A: Need another 4Gb card 2. When I go to SLI in the near future do I need the same card, a.k.a the same design? The reason I ask is I remember years ago I could have swore that SLI needed the reference design or the same card if not ref, correct?