Operating System :Windows 7 Home & Pro. MAR, Windows 10 Home & Pro MAR, Ubuntu Linux, Free DOS Chipset :Intel® 5520 Processors :Four-Core and Six-Core Intel Xeon Processor 5600 Series Memory Support :12 DIMM Slots for DDR3 ECC, 3-channel 800/1066/1333 MHz DDR3, Up to 192GB Hard Drive :250GB to 3TB SATA 3.0-Gb/s, 300GB to 600GB SAS, 128GB to 300GB SSD Drives Removable Media :16X DVD-ROM SATA Drive, 16X DVD+/-RW SuperMulti SATA Drive, Blu-ray Writer Expansion Bays :External: Three (3) 5.25-inch, Internal: Four (4) 3.5-inch Expansion Slots :2 PCIe x16 Gen2 Slots, 2 PCIe x8 Gen2, 1 PCIe x4 Gen2, 1 PCIe x4 Gen1, 1 PCI Slot Graphics :N/A Audio :High Definition integrated audio with internal speaker Communications :Dual integrated Broadcom 5764 Gigabit LAN I/O Ports :Front: Three (3) USB 2.0, Headphone/Mic, Rear: Six (6) USB 2.0, 2 PS2, 1 Serial, Audio I/O Power :Choice of 850W, 85% or 1110W, 89% Power Supplies Dimensions :44.4 x 20.3 x 52.5 cm; 17.5 x 8.0 x 20.7 inches Weight :21 kg (46 lb)