I thinking of sli'ing my gtx 570 to get me through the year till some newer cards come out. With the shortage of 570 cards out there I'm unable to find an exact match to my current card. My current 570 hd has 2 gb of memory while some of the other cards I found are SuperClocked but only 1gb. If I do decide to sli, which card should i use as the primary? Will Core speed or memory provide the best results for a gaming rig? Thanks