Operating System : Windows 8.1 Professional, Windows Embedded POSready 8.1, Windows 7 Professional, Windows Embedded POSready 7, FreeDOS Processors : Intel Pentium G, Intel Celeron, Intel Core i3,i5,i7 4th Gen Memory Support : Four (4) DIMM slots, up to 32 GB DDR3 SDRAM Hard Drive : Two 3.5 inch Sata HDD 7200 rpm or SSD Removable Storage : DVD-ROM/RW Expansion Slots : Two (2) Full-Height Slots, Can be configured either as two (2) PCI or two (2) PCIe x1 Full-Height slots, Two Half-Height, One (1) PCIe x16 (wired x4), One (1) PCIe x16 (wired x16) I/O Ports : Front : Two (2) USB 2.0, Rear: Three (3) USB 2.0, Two (2) USB 3.0, One (1) 24V powered USB, Two (2) Serial, PS/2, RJ-11 Cash Drawer Port, VGA , DVI, DisplayPort, Audio I/O, RJ-45 Communications : Intel I217LM GbE integrated network connection Dimensions : 37.9 x 33.8 x 10 cm Weight : 6.84 kg