If you’re shopping for a new graphics card for your desktop, you might have seen different models with different descriptions on the cooler units attached to the card—like “blower” or “open-air” cooler. Let’s take a look at what those terms mean for your GPU.

Both devices accomplish the same task: moving heat away from the central processor on the graphics card using a heatsink and a fan. This is a fundamental principle used in almost all desktop CPUs and most laptops: spread the heat from the processor out across a big brass or aluminum surface area and then move some cool air around it to get rid of the heat. The fans on your PC case itself do the same thing. The intake fans bring cool air in, and the outtake fans expel the hot air that’s been warmed by your computer’s various parts.

An open-air GPU cooler has exposed heatsink fins on the top and bottom. A blower GPU design covers these fins with plastic.

For a GPU, the difference comes in how those fans on your graphics card get rid of that excess heat. Both kinds use one or more fans on the cooling unit, mounted on the external plastic casing and drawing power from the card itself. These fans take in the hot air from the inside of your PC case. They don’t expel air out into it—at least not immediately.

An open-air GPU cooler takes in air from the fan, spreads that hot air over the heatsink, and then expels the warmed air back out into the interior of the case through openings on the top and bottom of the graphics card. That’s why it’s called “open air,” because there’s nothing between the heatsink connected to the GPU’s graphics processor and the air inside the case. The airflow looks something like this, with blue arrows representing the cool air brought into the graphics card by the fan and red arrows representing hot air expelled past the heatsink back into the interior of the PC:

An open-air cooler has its heatsink exposed to the outside of the card and expels hot air directly into the case.

In contrast, graphics cards with a blower design extend the protective plastic on the cooler all around the heatsink, including the top and bottom of the card. The only open area is a few holes in the mounting plate, the portion of the card that connects to the PC case and holds the electronic ports you plug your monitor or TV into. With the fan drawing in air from the case and nowhere for it to go but out the grille, the hot air that’s been warmed by the GPU heatsink is expelled completely out of the back of the case. This is also sometimes called a “rear exhaust” design, for obvious reasons. Here’s what that looks like:

A typical blower-style GPU, expelling hot air completely out of the case. Note that you can’t see the heatsink from the outside.

So which one is better? That depends on your setup. For a conventional desktop PC with a big, roomy case and a few case fans, open air coolers tend to perform better, cooling the GPU to a marginally greater degree. That’s because they have better airflow with fewer obstructions. Even though the system is using the warm air that’s already inside the case, having that extra flow will keep your GPU a little cooler.

But just because an open-air GPU cooler is better at cooling doesn’t mean it’s always the best choice. Because it’s so dependent on the air flowing well inside the CPU case, an open-air cooler will not work well if your case doesn’t have adequate airflow. If you’re using a smaller Mini-ITX case with fewer fans, or you depend on a water-cooling radiator for either intake or exhaust, the extra heat added to the interior of your case isn’t going to be managed as well. It’s going to make your GPU, not to mention all of your other components, run hotter and less efficiently. For smaller cases and those without a high amount of airflow, a blower cooler on the GPU that expels hot air outside of the case might be better for the system overall. 

For most users, the differences between the two types of coolers are minimal—less than five degrees of heat one way or the other, usually not enough to trigger lower performance. And of course, high-end users wanting to more precisely manage their interior airflow (or make for a cool-looking PC) might use a liquid cooling setup, which expels air via a radiator anyway. Unless you have very particular needs for your PC case’s airflow, don’t let the blower-versus-open air issue bother you too much.

If you are building a smaller case or you’re planning on using liquid cooling on your CPU, go for a blower GPU cooler design if the cards are comparable in other respects. If you’re planning on overclocking your GPU and you want maximum performance in a large case, choose an open-air design.

 Image credit: Newegg