Complex sentence: They currently advertise that their line of Killer computers is some of the best custom desktops in the world, built from the best hardware available from companies like Nvidia, ATI, and Intel.
Split into simpler sentences: They currently advertise that their line of Killer computers is some of the best custom desktops in the world. The hardware inside of their systems shows to only use top of the line technology from companies like Nvidia, ATI, and Intel.