1 - GeForce GTX 660 supports PCI Express 3.0. The Intel X79/SNB-E PCI Express 2.0 platform is only currently supported up to 5GT/s (PCIE 2.0) bus speeds even though some motherboard manufacturers have enabled higher 8GT/s speeds. As with the GeForce GTX 660 Ti, NVIDIA set 2 GB as the standard memory amount for the GeForce GTX 660. A 192-bit wide memory interface, populated with six memory chips of the same 2 Gbit density, should, typically, result in a memory amount of 1.5 GB. NVIDIA populated two of the six 32-bit wide paths with two piggy-backed 2 Gbit chips, each.