Restored Dell Optiplex 990-SFF WA1-0423 Desktop PC with Intel Core i5-2400 Processor, 4GB Memory, 1TB Hard Drive and Windows 10 Pro (Monitor Not Included) (Refurbished) - Walmart.com
Refurbished: Dell OptiPlex 990 SFF Desktop Intel Quad Core i7-2600 3.4GHz 8GB DDR3 RAM 500GB HD DVD-RW WiFi Microsoft Windows 7 Professional 64-Bit - Newegg.com
Dell OptiPlex 990 USFF – Specs and upgrade options
Amazon.com: Dell Optiplex 990 SFF Desktop Business Computer PC - Intel Core i5-2400 3.10GHz 8GB DDR3 RAM 128GB SSD DVD Windows 10 Professional (Renewed) : Electronics
Amazon.com: Dell Optiplex 990 Small Form Computer Tower PC, Intel Core i5 3.1GHz, 8 GB Ram, 500 GB HDD, DVD-RW, WiFi (Upgrade Up to 16 GB Ram / 512 GB SSD /
OptiPlex 990 Service Manual (Small Form Factor)
Refurbished: Dell Optiplex 990 SFF - QUAD CORE Intel i5-2400 - 1TB 7200RPM HDD - 8 GB DDR3 RAM - WiFi - Dual Video Output - DVD-RW - Windows 7 Pro 64-Bit Operating System - Newegg.com