1 x 5.25" & 1 x 3.5" Front Access Drive Bays. 2x 3.25" Internal Drive Bays. 3 Expansion Slots. Motheboard compatibility: Full Size ATX, Micro ATX (using optional A2423 upgrade kit), Mini ITX. Fits Standard ATX PS II PSU. USB2.0 & 1394 ports & HD Audio. Build-in Riser Card: PCI-Express x 1, PCI x 2. Removable HDD Cage for Easy Installing 3.5" Hard Disk. Dual 80mm Side & Front Fans. EMI Clips Design