In order for you to play Saints Row IV on Linux with minimal graphics settings, your computer must meet the following requirements
Operating System:
Ubuntu 14.04.3 LTS or SteamOS Brewmaster
Processor (CPU):
Intel Core i3-2100 (3.1 GHz) or AMD Athlon II X4 645 AM3 (3.1 GHz)
Memory (RAM):
4096 MB RAM
Graphics Card:
GeForce GT 440 (1024 MB) or Radeon HD 6670 (1024 MB)
Storage:
10 GB available space
In order to play Saints Row IV on Linux with maximum graphics settings, you need a computer with a configuration no worse than the following
Operating System:
Ubuntu 14.04.3 LTS or SteamOS Brewmaster
Processor (CPU):
Intel Core i5-2500K (3.3 GHz) or AMD FX-4300 (3.8 GHz)
Memory (RAM):
8192 MB RAM
Graphics Card:
GeForce GTX 660 (2048 MB) or Radeon HD 6970 (2048 MB)
Storage:
10 GB available space