Cooling Power
Corsair H45 and Corsair H55 provide different levels of cooling power. In general, Corsair H45 is more powerful, recommended if your computer tends to get hot quickly and frequently. However, if you need a more space-friendly option, Corsair H55 is a great alternative that is already better than most standard fans.
Corsair H45 is capable of providing up to 94 CFM airflow with 3.65mm-H2O static pressure. This model is considerably more powerful than the H55 model. Corsair H45 will keep your computer cool even during an extended gaming session. If your gaming session typically goes for more than just a few hours, this liquid cooler will give the best performance.
Corsair H55 provides up to 57 CFM airflow with 1.9mm-H20 static pressure. Although it is not as powerful as H45, it is already quite better than most standard fans that are without liquid cooling. This model will keep your computer within safe temperatures when you are gaming continuously for several hours. Not very cool, but sufficient to prevent overheating.