Windows 7: whats the differece in 8x8 sli and 16x16 sli configurations on mobo's

my p8p67 deluxe 3.0 offers duel sli at 8x8 in pcie slots is this good or bad or do i need another mother board, i feel cheated that my mobo states quad sli capabilities im have a gtx 560 ti 2 gb gpu and plan on buy another, but ive found out that it only operates in 8x8 sli config. please someone elaborate in detail what this mean and is this still true full sli. thanks my other components are as follows, intel i7 2600k,32 gb of g skill ram, 120 ssd kingston hyper-x, 5 tb hhd 2and 3 drives,

It just means that when you have the two x16 slots occupied, they'll downclock to x8 speeds, so they'll both run at x8 x8. I doubt it'll affect performance to the point that you'll notice unless you're doing some intense GPU compute and rendering tasks.

So go ahead and get another 560ti with that motherboard. It'll still run perfectly well.