"With only sixteen PCIe 3.0 lanes available on a Z77 motherboard paired with an Ivy Bridge CPU, when we get to three or four-way GPU solutions these GPUs are itching to get more bandwidth. The Z77 specification limits us to three GPUs anyway, at x8/x4/x4. For some extra cost on the motherboard, we can add in a PLX PEX 8747 chip that effectively increases our PCIe 3.0 lane count, giving 32 PCIe 3.0 lanes overall.