Open your cabinet by removing the left side cover. Before proceeding make sure that you are well grounded in order to prevent your computer from electrostatic discharge (ESD). ESD can occur when working in your computer and will cause components you touch to no longer work properly. The best way to prevent it is wear an antistatic wrist band which is easily available in the market.
Accumulation of dust over fans and other components hinders air flow in your cabinet, which ultimately causes it to heat up and reduce the efficiency of your machine. Use a vacuum cleaner to get rid of the dust. If you dont have one, you can also use an air-pump used for bicycles, to blow away the settled dust. Make sure the cords are not hanging unevenly, cluttering you cabinet all over. Tie them together with rubber bands and keep them as much away as possible from fans. This trick is extremely effective as the air coming inside the cabinet can be diverted out without any disruption.
Still not satisfied with the performance?
Consider adding additional fans in your cabinet. There are mainly two types of fans available. Ball bearing type and sleeve bearing type. A ball bearing type fan is a better choice as they are more effective and outperform the sleeve bearing type. Check for vacant space available at front or back side of your cabinet to install a fan. One of the most important point to keep in mind is to know the direction of air throw by the fan. If done correctly, you'll find yourself with an excellent air circulation mechanism. Usually, there are directional arrows marked on the fan blades to help you.
That's it, you are chilled!