Crossfire is AMD technology for pairing AMD cards in sync. SLI is nvidia technology for pairing nvidia cards in sync. Not the same. Crossfire will work on any mobo that has 2x pcie x16 slots, but sli is more picky and will only work on boards that say it will, usually the higher grade boards. Considering the sheer lack of decent crossfire support in games, it's not a major selling point anymore.