Now, NF4 and NF3 are the cipsets. I think it is Neoforce or seomthign like that. If you can do SLI, it will say SLI. You can have an NF4 board with SLI, and you can have an NF4 board without SLI. NF3 was just the older chipset, and has since been updated, hence the NF4. I would really recommend SLI though, too much money for a very nominal gain in performance. At this point, it's not recommended.