Honestly speaking, the efficiency of air cooler depends a lot on your PC case and location of fans + ambient temperatures. All Air coolers do a great job compared to Stock coolers. But keep in mind that almost all air coolers work more or less the same. The maximum temperature difference you may achieve between different coolers may be as much as 5 degrees. If you are not in to very heavy overclocking, Then any air cooling unit will do a good job that you can get cheaply.