Your PC's performance means little if the gear at your hands, ears, and eyes gets in the way. High-quality peripherals turn raw frame output into control you can feel: a mouse sensor that tracks cleanly, a keyboard switch that actuates where you expect it, a monitor that shows motion without smearing, and audio that helps you place a footstep.
The right upgrade usually starts with the part of your setup that interrupts you most. If your wrist tightens after a long match, a lighter mouse or larger pad may matter more than another RGB keyboard.