First of all, pre-built computers come with some parts you dont want or need as well as useless software. On the other hand, building a computer lets you decide exactly what to put in it and what to install on your computer. That helps out by freeing the hard drive, but sometimes computer companies have great deals on their software bundles. If you know somebody that has the software, dont bother buying a pre-built computer. You can just use his/hers for free (unless they charge you haha).

Secondly, building a computer is usually cheaper since you dont pay for labor. All you do is pick out the parts you want in the computer, put them together, and install your software. Its really not as hard as you think it is and youll save some cash doing it. One the other hand, if you are absolutely lost when it comes to computers, then you should probably just buy one. Building a computer isnt hard, but its much easier if you have a basic understanding of computers.

Thirdly, there is no warranty when you build computers. Since it doesnt come from a manufacturer, there will be no damage protection for it. If something goes wrong, youll have to replace the parts. The bad news? Well, youll have to spend some money to get it fixed. The good news? Itll usually happen after 2 years which means it needed to be upgraded anyway. The warranties by Dell or Gateway arent free and they will charge you even more if you want it for 2-4 years and during that time, you can not upgrade your computer yourself or else youll void the warranty.

So if you like do-it-yourself projects or love complete control over your computer, building a computer is for you. If you dont even want to think about it or think you might need a warranty, then buying a computer would be best for you.