In this YouTube video, EK Water Blocks discusses the advantages and disadvantages of an open and closed-loop water system. A person will choose one or the other based on their needs.
A closed loop water system called an AIO (meaning only one) means that the cooling system is completely closed off. The liquid cooling system cannot be expanded, opened, or maintained.
Closed loop water systems do not require maintenance. These units combine all the necessary components of a liquid-cooling system, such as a heater, radiator, and other required parts, into one piece of machinery.
AIO units contain a CPU water block and a copper plate. The pump, which is most likely located in the CPU, will be smaller than other systems and is subject to lower power pumps due to size constraints. The barbs and radiator are also included. Radiators are usually made of aluminum due to lower costs. In addition, the sealed cooling unit prevents corrosion due to the mixing of aluminum and copper metals.
An open-loop liquid cooling system is a custom cooling system that can be expanded on, opened, and maintained. Open-liquid cooling parts can be replaced or upgraded, as necessary. However, these cooling systems require yearly maintenance.
The open-loop liquid cooling system allows customization options for every single piece of the system. These systems have CPU water blocks that are separate from the pumps and the radiator. In addition, there are no size restrictions on these systems, allowing more powerful pumps.