Intel DX48BT2 Extreme Series X48 Desktop Board, ATX, DDR3 1600, 3xPCIe x16, 1600MHz FSB, LGA775, Retail Motherboard ATX Form factor Gigabit LAN 4 Memory Slots (up to 8GB), DDR3 1600/1333/1066/800 Intel X48, 1600MHz Bus Speed Full Supports Crossfire X 16x16x4x PCIe 2.0 x16 8 Channel Audio Support, SPID out with Dolby Digital Live, Dolby Digital ProLogic II, Dolby Digital Speaker, Dolby Digital HeadPhone.