What are the drawbacks of add on cards?

The only major drawback to add-on cards is that they need to be installed. This process requires the case be opened (powered off and cables removed, label them if you are not sure where they go) and a blanking plate removed. The add on card would then be inserted into the open slot, seated properly and then the screw replaced. If you are uncomfortable doing this, most local PC repair shops will install the card for you. Things to look out for: does the new add on card support your Operating system, and does in have the proper drivers with it. Most add on cards add features, or functionality to a computer, or improve the embedded devices on your motherboard. A good example is that most retail computers have the video graphics embedded on the motherboard. They are fine for normal graphics and web stuff, but if you want to play serious games, a add on graphics card with decent memory is better. Hope this helps.