Would SLI work with different amounts of RAM?

I have  galaxy GTX 670 (2gb) and I've been thinking about grabbing another GTX 670, what would happen if I got a 4gb GTX 670? Would it SLI properly? Would it run higher resolutions better than 2gb or would the extra 2gb's on the 4gb card not work or something? Thanks for any answers 

For example, if you had a GeForce GTX 770 2gb and a 770 4gb edition, you could; but the memory would only be as high as the card with the lower ram. The processing power would combine, but the memory (RAM) wouldn't because the lower card can't match the memory stored on the other card. Now remember, if you're going to SLI the cards, put the larger card in the primary PCI-e so that it will utilize the power of the stronger card before using the boost given to it by the other one. Now, keep in mind that you CAN NOT crossfire/SLI a GeForce and Quadro, or Nvidia and Radeon.

hope this helped!

If i remember right Linus said that the core and ram have to be the same. https://www.youtube.com/watch?v=cxc6cb3_y0w


Thanks to both of you!