Pretty much all motherboards support Crossfire even if they don't specify this so long as they have enough PCIe x16 slots. That's an advantage of Crossfire over SLI in support, granted not a major one. SLI support is not as simple, so if it costs more to get a board that states it has it, then it costs more to get a board that supports it. Don't spend more to get it if you don't intend to use it. Still, I agree with the above post in that you should tell us what motherboards you are looking at. The more expensive one may have more than SLI support going for it for all we know until we can have a look.