Computers need fans inside the case to keep all the electrical components cool. If they overheat your computer will stop working and it can even destroy the hardware you have installed. Replacing a defective fan can mean the difference between a small expense and replacing the whole computer. You do need to be careful and pay attention to detail when replacing a computer fan. The first thing you need to do is determine what size fan you have in your computer case. You will want to replace it with a fan that is the same size, this does not mean that you cannot get a fan that is a little more powerful, but the measurements need to be the same so that it can be mounted in the same spot inside the case. Some computers come with more than one fan or slots where you can add more fans if you find that you need them for cooling. For instance the case I am using right now has three fans installed in it. This could be a good idea if you live in an area where you get consistent high temperatu