Operating System :Windows 7 Home & Pro. MAR, Windows 10 Home & Pro MAR, Ubuntu Linux, Free DOS Chipset :Intel® C206 Processors :Intel® Xeon? E3-1200 series or 2nd generation Intel® Core™ processors. Memory Support :4 DIMM slots; up to 8GB 1333MHz non-ECC memory; up to 16GB 1333MHz ECC memory Hard Drive :Up to two 3.5" SATA drives: 250GB, 500GB, 1TB, 2TB; Or up to four 2.5" SATA drives: 320GB, 500GB Removable Media :CD-RW/DVD Combo, DVD-ROM, DVD+/-RW, Blu-ray Disc?, USB Floppy Drive, USB media card reader Expansion Bays :Two internal 3.5" bays accomodate two 3.5" or four 2.5" drives; two external 5.25" bays Expansion Slots :One PCIe x16 Gen 2; one PCIe x16 Gen 2 (wired x4); one PCIe x1; one PCI. Graphics :One or two PCI Express? x16 Gen 2 discrete graphics cards supporting 75W maximum combined power Audio :Integrated High-Definition Audio Communications :Integrated Intel® 82579LM Gigabit LAN I/O Ports :Eleven USB: four on front panel, six on back panel, one internal; one serial; two PS/2; Line-in, line-out, mic Input Devices :Dell Enhanced QuietKey USB or optional: Enhanced Multimedia USB or Smart Card keyboard USB Dell USB two-button mouse or optional Dell USB optical two-button scroll mouse Power :265W 65% Efficient Power Factor Correcting (PFC) or 320W 90% Efficient Power Factor Correcting Dimensions :(HxWxD): 14.17" x 6.89" x 16.99"; 360mm x 175mm x 431.5mm Weight :N/A