Ue4 lightbuilding question

Hello, i have searched online for what is the best system to put together for working on unreal engine 4. fro example for 3D rendering i know that the CPU is the most important part for the computational process. what is responsible for the light building process in UE4 and what is the hardware responsible for packaging as well? and what is the best system to put together for optimal UE4 experience with around a 5K budget? the aim is to be able to test light building fast ,and light build for production as fast as possible.

awaiting your reply guys thank you in advance :smiley: