Gaming Rig: is common slang for a desktop computer, especially a custom-built computer: purchased, assembled, and configured to be a high-end computer optimized for gaming.  Nowadays, a modern gaming computer is comparable to a mainstream computer with the addition of performance-oriented components, such as video cards and high core-count CPUs.

Example specs of a gaming rig are the following:

GPU: GeForce GTX 1070

CPU: AMD Fx-8350 Eight Core

Keyboard: Benq Celeritas II

Mouse: Patriot Viper Gaming V570 RGB

Audio: Etymotic Research ER4P Earbuds

Mic: Blue Yeti Microphone

Webcam: Logitec C920

2x Acer Monitors 144hz