SLI is a licensed (BIOS Key) from nVidia, and the overwhelming vast majority of LGA 1155 that offer SLI are 2-WAY. Cross-Fire (CF) on the other hand is only limited to the number of available PCIe slots that you can 'fit' the AMD/ATI GPUs into, and then in most cases it's x8/x8 or x8/x8 + x4. Further, the limit is 4 GPU cores so SLI/CF 2-WAY (2*2 core) with GPU's that offer 2-cores (e.g. GTX 590 and HD 6990). Also, even with the 'x4' the 'GEN3' switches don't affect those PCIe slots.
And don't even want to try to explain (short of a book) the 4-WAY SLI/CF on the NEWEST LGA 1155 (Z77's), in short a different chipset that splits the PCIe 3.0 (requiring an Ivy Bridge CPU) into x4/x4/x4/x4 PCIe 3.0 -> into -> x8/x8/x8/x8 PCIe 2.0.