Lenovo ThinkCentre M73 SFF Intel i5-4570 3.20Ghz 4GB RAM 500GB HDD Win 10 Pro (Certified Refurbished) 3.2GHz Intel Core i5-4570 Quad-Core Processor (4 threads, 6MB cache); Intel HD Graphics 4600 4GB (16GB Max) DDR3-1600 SDRAM, 500GB 7200rpm SATA 6.0Gb/s Hard Drive, DVD-Writer 2 x USB 3.0, 4 x USB 2.0, Serial, VGA, RJ-45, DisplayPort, 2 x PS/2 Gigabit Ethernet, High Definition (HD) Audio, Internal Speaker (1 Watt), USB Keyboard and USB Optical Mouse Windows 7 Professional 64 preinstalled through downgrade rights in Windows 8 Pro 64-bit; 3 Years Limited Warranty