Sophisticated Performance Refined. XL-ATX Standard ATX microATX Mini-ITX mobo compatability 9 expansion slots with 4 designed to hold 13" GPU cards Top power switch USB 2 x 3.0(internal connect) 2 USB2.0 Audio I/O HAD-AC'97 3 5.25" tool-less drive bays 2 x 2.5" drive bays 6 x 3.5"/2.5" drive trays w preinstalled silicone groumets max CPU height 6.7" triple-layer front door w double hinge.