How to perform pc bench-marking in computers?

For bench marking your computer, you should use Pass Mark Performance Test software. This software will allow you to objectively benchmark your system by using a variety of different speed tests and even compare the results to other computers. You will be able to

• Find out if your system is performing at its best.
• Compare the performance of your machine to similar machines.
• Measure the effect of the configuration changes and upgrades.
• Avoid paying big bucks for poor performance.
• Make objective independent measurements on which to base your
  purchasing decision.
• Use the advanced tests to create you own benchmark scenarios

You can log on to to the link given here, http://www.passmark.com/products/pt.htm and download the software.