Operating System :Windows 7 Home & Pro. MAR, Windows 10 Home & Pro MAR, Ubuntu Linux, Free DOS Chipset :Intel C612 Chipset Processors :Intel® Xeon? Processors: E5-1600 v3 family or E5-2600 v3/v4 family Memory Support :4 on board(CPU0) + 4 on optional 2nd CPU Module(CPU1), DDR4, RDIMM/LRDIMM (Registered). Up to 256GB Hard Drive :250GB to 4TB SATA 3.0-Gb/s, 300GB to 1.2TB SAS, 128GB to 512GB SSD Drives Removable Media :9.5mm Slim SuperMulti DVD Writer, 9.5mm Slim DVD-ROM Drive, 9.5mm Slim BDXL Blu-Ray Writer Expansion Bays :External: Two (2) 5.25-inch, Internal: Two (2) 3.5-inch Expansion Slots :2 PCIe x16 Gen 3 Slots, 1 PCIe x8 Gen 3, 1 PCIe x1 Gen 2, 1 PCIe x4 Gen 2, 1 PCI Slot Graphics :N/A Audio :Integrated Realtek HD ALC221 Audio Communications :Integrated Intel I218LM PCIe GbE Controller I/O Ports :Front: 4 USB 3.0, Headphone/Mic, Rear: 2 USB 2.0, 4 USB 3.0, 2 PS2, Audio I/O Input Devices :Standard Keyboard (USB or PS/2) Mouse (USB or PS/2) Power :925W, 90% Efficient Power Supply Dimensions :44.45 x 17.15 x 46.48 cm (17.5 x 6.75 x 18.3 in) Weight :17.9 kg (39.4 lb)