The effectiveness and quality of a computer dissertation depends quite a lot on the area or topic which was chosen for the research. If the topic is interesting and appeals to the reader in the sense that it provides something new for the human imagination then there is a very good chance that the whole report will be interesting to read and will motivate a lot of people to actually read the whole report rather than discarding it just by reviewing the topic. Thus you have to select a theme very carefully and several steps can be taken in this regard. The first thing to do when you are deciding about the subject is to examine previously completed researches on various topics. Try to find the one which interests you personally and then start building on that idea. Try to search for similar themes from various sources including books, forums and magazines while seeking advice from professors and your supervisor. Once you have decided on a particular area of research produce five to six themes on that area and discuss with your supervisor to narrow down the topic of your computer science dissertation topics until you eventually end up with the best and most effective topic.