Extension cords are great for connecting short and long cords together. For instance, if you have a small power tool you need to use in another room or outside in the garage, you will need an extension cord. An extension is meant to add length. The biggest problem most people run into is actually a simple one. If they would take a few minutes to check the watts and recommended wiring specifications of a cord before they use it that information could prevent a lot of house fires.Get more information here. http://gizmodo.com/5903218/how-to-choose-the-right-extension-cord-for-anything
Fires associated with using extension cords happen when people overload the watts. Electrical cords are sold and used according to their weight and purpose. For instance, if you need to plug in an iron you would use a regular lightweight extension cord because the iron does not require burning a lot of watts.
To operate a computer you would definitely need a heavy gauge cord. The heavier the size of the electrical cord is the more money it costs. However, no one should put a price on safety. Stay safe take a close look at the wiring size before plugging up an appliance or other electrical device. Be sure it is within the AWG system guidelines. Never overload your extension cord with more watts than it can deliver.