I am planning on making my first computer build soon. I am planning on getting an Intel i5-2500K Processor for the build. I have heard that the stock fan for it is not very ideal. What I want to know is will a Corsair H100 be a big improvement over the stock fan or should I just stick with it?
The H100 would be a very big jump in cooling performance if you're looking to do some overclocking. It's the best simple liquid-cooling solution out there so far, and does slightly better than the best air-coolers in most benchmarks I've seen thus far.
The reason people buy I5 2500K's IS to overclock them! If you want to play the newest games at Max settings, you will probably want to overclock. Cooler Master Hyper 212+ or EVO model wiill be all the cooling you should need.
Would playing a video game on max graphics be enough to become overclocking?
Overclocking a cpu is manually changing the speed that the processor runs at (this assumes you are setting it faster than stock, if you going the other way it is called underclocking).. which is done either through the bios or through various programs such as AMD overdrive in your OS. Computer usage has nothing at all to do with overclocking, so in answer to your original question.. stressing your computer through gaming does not overclock your computer for you.
i recently got a i7-2600k and a Corsair H100. Not sure how the heat of the 2 cpu's if different, but overclocked to 4.8 Ghz, my CPU idle's at about 30 C. and highest i've seen it jump is 40 C when i play FFXIV or batman Arkham City, max settings. Not sure if these games do that or its backround processes but, I'm pleased with the buy.