One card has 4 gig mem and the other 2 which stops the option for SLI from showing in control panel. Installed coolbits 2.0 REG entries. Option available but will not support any games and plays hell with windows among other things. So the card will be heading to UPS which is a real bummer. I was so excited only to be shot down. Why hasn't NVIDIA taken care of this issue? It seems so stupid to me.