How many years of college do you need to be a computer technician?

Yes, at least 2 years and you need to do much practice. Remember that all that you learned from school or books can not make you become a good computer technician, only practice can unless you are a genius.
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Technically none. Computer tech jobs are within reach of most people that can prove they know what they are talking about. If you don't already know what you are doing, then you'll need schooling, or a pretty big interest to get yourself motivated to learn quickly. These jobs usually don't pay great, but if you specialize in one particular area (like unix administration, or networking), then you can usually increase your pay to a moderate level. The good "engineer" type jobs usually require a 4-yr BS in CS, or IT, IS, CE, or some related program. Most companies will accept "equivalent experience" but you've really got to know what you are doing to get into high level paying positions.
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If you want to be a "Certified" IT Tech, CompTIA (the organization that gives IT certification) will give you certification by passing their exams, which are around 140$ per test . For the basic computer repair certification (A+ certification) you have to pass the CompTIA A+ Essentials and CompTIA A+ Practical Application exams which have around 100 questions each for more information see http://www.compTIA.org to find testing centers see http://www.prometric.com or http://www.pearsonvue.com. There Votech schools that offer A+ classes such as the class i am currently taking at Crowley's Ridge Technical Institute that offer courses that prepare you for the A+ and Network+ exams.