Open Box: HP Desktop Computer ProDesk 400 G3 MicroTower (P5U87UT#ABA) Intel Core i5 6500 (3.20 GHz) 4 GB DDR4 500 GB HDD Windows 7 Professional 64-Bit (available through downgrade rights from Windows 10 Pro) - Newegg.com
HP ProDesk 400 G3 Microtower PC Software and Driver Downloads | HP® Customer Support