I presently have a 2GB 670, and have been offered a second 4Gb one at a great price, both are built off the 680 PCB (windforce 3x versions)

Theres very mixed messages about on google about whether SLI with the same cards with different VRAM sizes works or not, I suspect not helped by the fact that some of the problems may be from cards that are available with DDR3 and DDR5.

Has anyone successfully got it working? Unfortunately the other card is a distance away so I can't just try it out.