A single card will run at x16 speeds, dual cards will run at x8 x8 speeds. There's barely a difference between the two so you should be set for sli or crossfire.
A single card will run at x16 speeds, dual cards will run at x8 x8 speeds. There's barely a difference between the two so you should be set for sli or crossfire.
mean the motherboard can handled 16. if you only use one card, that one card can use all 16. if you have 2 cards, it will have to divide it to a max of 8.
like RazerZ said, you might not noticed any different. Which card are you trying to sli?