i found this dell optiplex 755 in a scrap yard perfectly functioning{came with side panel just have it off} its ungodly slow with only a single stick of ddr2 2gb ram and
Dell OptiPlex 755 Dual Core 1.60GHz 4GB DDR2 160GB HDD Windows XP *Reconditioned
Refurbished: Dell Optiplex 755 A Grade Desktop PC with Intel Core 2 Duo 2.66GHz, 4GB RAM, 1TB HDD, DVDRW, Windows 7 Professional 64 Bit, Microsoft Authorized Recertified Desktop PC w/1 Year Warranty - Newegg.ca
Dell OptiPlex 755 Repair - iFixit
Refurbished (Excellent) - Dell Optiplex 755 Ultra Small Form Factor PC: CORE2DUO 2.0GHZ/4G RAM/160G HDD/DVDRW/WINDOWS 10 - Certified Refurbished | Best Buy Canada