As a custom computer manufacturer, we’ve sold liquid-cooled systems from well before I joined the company. A water-based coolant is able to transfer heat away from hot components like the processor (CPU) and video card (GPU) more quickly than air alone would. That added cooling is appealing for folks who want to push their systems beyond design specifications. Overclocking ability is perhaps the most the most tangible benefit of liquid-cooling, but there are other reasons some folks are interested in it: liquid-cooling can make a computer look very stylish, for example, or allow operation of more hot-running components than a chassis could normally keep cool.
Traditionally, custom liquid-cooling of computers is achieved through a combination of several separate parts: A pump to move the fluid, a reservoir to hold excess coolant, one or more radiators with fans to cool the liquid, and ‘water blocks’ on each of the various components to be cooled. These are all connected via tubing specially cut to fit the exact hardware setup. Such configurations are effective at cooling CPUs, GPUs, and sometimes even the chipset, RAM, or hard drives. However, the large amount of separate parts involved and complexity of setting it up added substantially to the cost of a computer. A system cooled in this way can easily cost $1000 more than the same hardware with standard air-cooling components. There is also the risk of a coolant leak, as there are many seals which could degrade or loosen over time.
To combat both of those downsides, a setup called closed-loop liquid-cooling has been gaining popularity in the last few years. Closed-loop liquid-cooling describes a self-contained cooling system which is manufactured as a single unit and pre-filled with coolant. These units are much more cost effective than traditional liquid-cooling configurations, and are virtually impervious to leaks. In trade, they offer more limited options and performance -- most CPUs can be cooled this way, and select video cards, but that’s about it. These systems are really more like souped-up heatsinks than traditional liquid-cooling systems. Closed-loop systems are a single fixed unit, not a conglomerate of customizable parts. There’s nothing wrong with that, and I personally prefer these types of setups - just so long as you know what you are getting, and it makes sense for your needs and situation.
What can become tricky is determining which of these solutions is being utilized when you go to purchase a computer. Many companies advertise the latter option as “liquid-cooling,” which is technically correct, but can cause confusion when comparing prices. Here at Puget Systems we reserve the liquid-cooled section of our website for only those systems using traditional, customizable liquid-cooling setups. Our closed-loop CPU liquid-cooling unit, the Puget Hydro, is shown on the air-cooling configure pages instead - as our top-end CPU cooling option. We do blur the line a little in our Deluge gaming computer line, where we have configurations both with the more affordable Hydro and the full cooling options, but it is usually clear from the pictures and naming what each computer uses. The price is also a giveaway: as mentioned above, traditional liquid-cooling adds several hundreds of dollars to the price of a computer - whereas the smaller, self-contained units are on-par with high-end air cooling units in terms of price.
Noise level is another aspect of liquid-cooling about which there remains some ongoing confusion. Traditional liquid-cooling can reduce the noise level on a system with extremely high-end hardware (particularly video cards) when air-cooling would make copious amounts of noise. However, liquid-cooling is not truly quiet in the grand scheme of things: there are still fans for cooling the liquid as it passes through a radiator, as well as fans in parts of the system not reach by the coolant. Plus, you are adding noise in the form of a pump to provide circulation. For a truly quiet system air-cooling is often better, but it has to be done very carefully. If that is your goal, something along the lines of our Serenity systems is the best way to go.