Hp Motherboard For Hp Z400 - System Board ( 1 ) One Fclga1366 Socket ( Compatible With Legacy Intel Xeon Processors - Bloomfield ) ( 4 ) Four Ddr3 Dimm Slots Up To ( 4 ) Four Pci-e 2.0 / 1.0 Interfaces ( 2x16 G2 1x4 Gen2 At X4 Speed + 1x4 Gen1 At X4 Spee