Fans help circulate air through a system, be it a desktop or laptop PC. The more fans installed, the better the airflow, and the more heat can be exhausted. Purchasing the best PC case fans for your system is only step one. The second step is to install the blowers and connect them to your motherboard or hub. But when installing the fans onto a radiator, which is usually the case with AIO kits, is it better to configure fans in a pull, push, or push-pull configuration? Does it even matter?

What is push, pull, and push-pull?

Push, pull, and push-pull is the directional setup of a fan. A fan typically pulls air through and pushes it out the other side. If a fan is configured for "pushing," it attempts to blow air through the front of a radiator. "Pulling" is where the fan sits behind the radiator and attempts to pull air through the fin stack. Push-pull is when there are fans on either side of the radiator. One fan pushes air into the radiator and the other pulls it through the other side. Some fans may even be preinstalled on the radiator from the factory in a specific configuration.

Which configuration is best for PC fans?

The best configuration for radiator fans is push-pull. This offers the best performance by forcing as much air through the fin stack as possible and allows for more densely packed fins that help to increase heat transfer. If you're only using a single row of fans, push or pull will have a negligible effect on the cooling performance of the AIO. Your CPU (and any other hardware connected to the loop) will run just as well with either setup. There can be cases where this may have an impact but the only way to tell would be to try each configuration and check temperatures.

I ran tests using the trusty AMD Ryzen 7 9800X3D, iBuyPower's AW4 360 AIO liquid cooler, and some PC games. Although your mileage will vary, depending on the CPU, cooler, case, and ambient temperature, I found the push-pull configuration to offer the best cooling performance. As expected, there was very little to separate the other two fan setups. The above results were measured playing Cyberpunk 2077 at 4K. In the end, it doesn't really matter much, though doubling up the fans on your radiator can make a small difference and allow for slower spinning blades.