The Problem
While doing some moving for a family member, I scored a older desktop tower with an i7-4770, 12GB of RAM, and a 1TB SSD, but no GPU. This was a great starter computer, but lacked a GPU.
The Diagnosis
The tower, a HP Envy 700, is a standard ATX desktop, and therefore could be upgraded with spare parts. I decided to upgrade this tower with a GTX 1080, A new 802.11n NIC, and a more powerful PSU to support the whole thing.
The Changes
I disassembled the system and cleaned it of all the dust bunnies. I replaced the CPU thermal paste and removed all old PSU connections, then installed the new PSU and reconnected everything. The Wi-Fi onboard was painfully slow, (802.11b) so I upgraded the NIC with one from a scrap laptop (802.11n). I zip-tied all the new cables and closed the tower.
The Results
The system now functions better than my own computer, and runs GTA V on full settings at 60+ FPS while managing to stay cool. I also tested it with other applications like Portal and Factorio. Wow!