The Intel i5 2500k really is an incredible CPU. For under £170 nothing else comes close. It's impressively power efficient and runs at a very reasonable temperature. Yet more importantly its performance is staggering- a genuine tour-de-force from Intel.
To start it overclocks brilliantly- a stable 5 GHz is possible with a good air cooler, whilst 4.7 or 4.8 GHz is a perfectly achievable everyday overclock, which should avoid excessively high voltages. That said you don't even need to overclock it in order to get good performance- its architecture and IPC are both brilliant and as such it offers great performance even at stock frequencies. The turbo feature is also very useful for anyone who doesn't fancy- or really need- an overclock.
Furthermore it bulldozes through applications (AMD can't hope to match it unfortunately) and is sensationally good in games. Just google 'i5 2500k reviews' and have a look at some of the benchmarks recorded. Sensational.
I remember being shocked when the i5 2500k was first released a year ago- despite costing a fraction of the price it gave the beastly £800 Intel hexacore i7 980x a decent run for its money, even managing to surpass it in less multi-threaded applications. I couldn't believe that Intel could possibly sell a £200 CPU which could match their king-of-the-hill £800 hexacore. This concept made no economic sense. And a whole year later the i5 2500k still remains the unchallenged mid-range king. The perfect trade-off between price and performance (much more of the latter). A remarkable achievement indeed. It even fares well against Intel's newest extreme hexacores (LGA 2011) which easily cost three or four times as much. The i5 2500k isn't the fastest CPU in the market (although it isn't too far off...), yet it offers by far the best value for money.
I used around about twelve of these brilliant CPUs in 2011- I used them in every single rig I made, for myself, for friends and for family- all were centred around the black magic of the i5 2500k.
So there you have it- as 2012 commences it appears there still isn't any worthy challenger to the i5 2500k. Someone bring me a bucket- I'm going to need a whole lot more of these :D