firstly thanks for the responses, asked that question because the specification of msi (http://www.msi.com/product/vga/N580GTX-Lightning.html #? div = Specification) contained only "3-way SLI: Y ". My motherboard is a Gigabyte GA-X58A-UD9, and I already have a n580 and I intend to make a 4-way sli