Okay, first you need to get your terminology straight. SLI is the nVidia equivilent of crossfire, it lets you use multiple cards to drive one monitor. What you have are nVidia cards, a single nVidia card will work fine on an ATI board, however you cannot use two of them in SLI. If you only ever plan to use a single graphics card it doesnt matter who made the card or your motherboard, a single card will work fine, its the multicard setups that get into compatibility issues.