Some how, some way, we need to teach every noob how to use the search function. Maybe they should all have to prove they know how to search for a topic before they get out of noob jail? Moderators, can we make this happen? Just some sort of test where they have to use the search function once before they are allowed to post "new" topics?
This is wishful thinking. If you really want to solve this problem, require that anyone who wants posting privileges post a bond, in Bitcoins. Some nominal fee like $25 worth of Bitcoins. If they break the forum rules, like posting something that could have been found via search, they forfeit the bond. Problem solved.