Not so much high-end CPU, but rather a high-end GPU is required to run games smoothly at high resolutions.
This. You'd need, like, a £300+ GPU to be able to effectively use that kind of resolution. You would also need a fairly decent CPU to run it, but a 2500K will cut it. If I were you, I'd stick to 1080p gaming, because with monitor and GPU costs, a system of the kind you are suggesting is just crazy expensive.