Not really a full guide.. more a point in the right direction...
Guide written and maintained by Chaos for WDG (if you are giving OCing a go and need more specific help, PM me and I'll usually be happy to help if I can)
Edit list is at the bottom of the post!
IntroWelcome to my collection of thoughs/materials regarding all things Overclocking and cooling.
Here you will find guides and advice to help you make the most of your hardware, be it making the most of a tiny budget or pushing your extreme machine to the max!
Why do it and what happens when you doSo you want to overclock? but not sure what it does and why your doing it eh? Well here goes...
Overclocking is pushing your computer components to run past their rated speeds. To do this youll need to get to know your computer well. But a good overclock can double your frame rates and performance in games/rendering ect. so if its done right it'll be worth the trouble.
Achieving good speeds means using more electrical energry and therefore more heat is produced by the parts, so you'll need to make sure your components wont fry themselves from overheating. This is where cooling comes in. There are many types of cooling from air heatsinks to water cooling loops to liquid nitrogen tanks.
GuidesA collection of guides I trust..
Some are dated, but the principals are the same
General TerminologyGeneral OC Guide, Bit dated, for older single core CPUsI suggest you read this if you are new to overclocking, to get to grips with how it works.
A good place to get startedThis one I would print out and use as you go.
Getting to grips with Air Cooling, some readingDoing it with water... the biginners bible!Useful Websites/Blogs ect..XtreemSystems Where the worlds best/manufacturers go to post results/information ect... first port of call for all research..
3dGameMan YouTube Channel/
3dGameMan Website and forum Good to keep up to date with the latest hardware for modern computers, he does very thorough reviews.
UK ShopsOverclockers UK Most of you know what this is, you can get pretty much anything you want at pretty good prices. They sell a lot of case modding/cooling supplies
Scan Computers UK Similar to Overclockers UK but sell some brands that they dont and vise versa, prices for parts vary between sites
eBuyer Dirt cheap PC parts, not much for the overclocker but sometimes can pick up a bargain.
Chilled PC Dedicated cooling/modding supplies store, prices are expensive but service is top! They also custom fabricate some parts and perform some cool custom case mods like anodising/CNC cutting ect..
Maplin Sells all sorts of electronic components, most of them are a bit dated but they have a large range of quality tools for sale that will help you make the most of your current/future computers
A lot more comming! I started this a while ago and never got around to finishing it... I have some time on my hands so Ill start it up again especially for you guys

Edit1: added intro secion
Edit2: added useful shop list/Why and what section