hemant_5,
Water Cooling can be really expensive, depending on the type of loop.
Custom: A DIY loop, connecting anything that you can buy a water block for e.g (RAM,CPU,GPU,Northbridge)
Custom are really expensive, and rarely done for their cooling efforts. Although they are very good at cooling hardware, the purchasing of radiators,water blocks,tubing, and fittings can make a
VERY inefficient Cooling to Cost ratio.
I dont recommend for you to make one.
Example:http://www.newegg.com/Product/Product.aspx?Item=9SIA6ZP3S84225
AIO's: Standing for "All In One's" are prebuilt, water-cooling loops, that can be expanded on traditional only include a CPU water block with a pump, and a radiator. These offer a
BETTER Cooling to Cost ratio, but can get quite expensive.
If you plan on Overclocking a lot, you may need one.
Example:
http://www.newegg.com/Product/Product.aspx?Item=N82E16835181090&cm_re=H100_GTX-_-35-181-090-_-Product
AIO-Hybrids: Are just like AIO coolers, and usually come prebuilt with a pump/reservoir,CPU block and radiator. They are quite expensive but can be worth it as they allow for expandability.
These can be a cheaper way of making a custom loop.
Example: http://www.ekwb.com/predator/
Water-cooling is for serious Overclock's.
If you just plan on trying Overclock, and aren't even sure if you've got a lucky chip, just go with a cheap air-cooler like this:http://www.coolermaster.com/cooling/cpu-air-cooler/hyper-212-evo/
The Hyper EVO 212 is great for Overclocking starters. If you find you need more cooling, you may want to invest in one of the above, water cooling options.
If theres anything I missed, just ask
~Nnokalad