For the enthusiast gamer the important thing to always have in mind is that they have to ensure a balance when combining CPU and GPU for their computer. Very fast processor and slow graphics card will have a negative impact on gaming performance same as slow CPU and fast GPU.Another thing that you should bear in mind is that games usually utilize 1 or 2 CPU cores, therefore a processor with virtually more than 4 cores is not necessary.Make shure your power supply is sufficient with starting point at 750Watts.
Intel Core i5 2500K (around £160) combined with nVidia GeForce GTX560Ti (around £170) is the best mid-range budget gaming CPU/GPU combination. Most of the newer games will play smoothly at 1080p resolution and high settings.
If you are an extreme gamer with an eye for the ingame detail then you probably are considering multi-monitor setup. Good starting point is a proper motherboard with space for at least two GPUs in SLI (read about SLI on Wikipedia.org).Certified power supply (at least 1000Watts) is a must! Latest generation Intel Core i5-3570K (around £170) or higher or AMD FX 8150 (around £160) processor and all that in a properly air/water cooled tower. Two nVidia GeForce GTX570 (around £220 each) in SLI or the newest generation nVidia GeForce GTX680 (around £440) will make your gaming experience incredible! Want to make it even better? Equip your gaming PC with a primary 128/256GB SSD (around £100 to £200) and enjoy.