4K monitors are getting cheaper and cheaper, while their sharpness can't be matched by normal displays. Graphics cards have to render four times as many pixels to drive a 4K display compared to a 'normal' Full HD panel, while the game textures are only getting more detailed. In short: you need real horse power to game in 4K.

A fast processor and especially a graphics card is a must. However, the rest of the configuration needs to be balanced as well. Since many gamers prefer to overclock their PC to improve performance, it is important to choose a motherboard that is suitable for this.