Liquid cooling is definitely a good option. They even have kits if you want to liquid cool only certain components, instead of running them through a pipe network and all the planning that involves.Overclocking is really a thing where you don't mind of it standing the chance of breaking the piece. Though you plan on changing cpu so I'd say you're pretty much ready to build a new one since new cpu mostly mean new motherboard. Unless you plan to find a cpu that uses the same pins as your motherboard.
When you do decide to build a new computer I'd suggest to use liquid cooling really helps with heating issues.