What is push-pull and does it increase performance for PC radiators?

Once you reach max level, do you stop leveling? That is a question that people start asking themselves after they have poured an absurd amount of money into their pièce de résistance. So you already custom cooled your system and put fans on every radiator you could get your hands on - now what? The answer is obvious. more fans = more better, right? This is where people start to consider what's known as a push-pull configuration.

If you find yourself with double the amount of fans you thought you needed, the obvious choice would be to put them in a push/pull configuration on your radiators. Push-Pull is exactly what it sounds like - two fans on a radiator where one pushes, and the other pulls air through. This configuration is most often seen in extremely large builds using cases such as the 9000D or older 1000D cases where there is so much room that it almost looks empty with just a push, or a pull configuration.

Push-pull is also most popular with thick radiators that have a high fin density to better force air through it (how close together the small fins in between the cooling channels on the radiator are - closer together = better performing radiator, but requires higher fan speeds to utilize that potential). Bigger gap in between the fins means that it is highly optimized for fans running at lower fan speeds as less force is required to move air through the radiator). Corsair radiators typically will used a "medium" FPI (Fins per inch) to achieve best performance in the mid-range RPM levels where noise is not too excessive.

We did a quick test showing if there is any difference to be had by going with a push-pull configuration. This test is not the most detailed in the world, but it gives you an idea of what to expect if you try a push/pull config.

We are running an ASUS 4090 STRIX card with Furmark for 30 minutes with a push configuration, and then 30 minutes with a push-pull configuration. The total load on the radiator is 500W from the graphics card. For this test we are using our LX120mm fans.

Only the radiator sitting on the table is connected to the system, with the two on the base of our display rig is disconnected. Pumps are both running at 4800RPM.

Results are underwhelming. Adding double the fans to radiators represents a significant investment, and running the fans at 1000RPM on the radiator only created a drop from 44c to 43c in coolant temps. Now, other factors will affect this with different setups such as which RPM you run the fans at, thickness of radiators and FPI as mentioned earlier. But regardless of these, the increase will likely still be in the few degrees range.

So the big question to be had is - should you do it? In our opinion, not as a first measure. The first priority you should have should always be to try to add extra radiators to your loop instead. Adding just a single 240mm radiator will provide you with much more cooling potential than adding more fans to an existing radiator.

So in short, push-pull looks cool and will increase your performance by a little bit, but you should always try and max out your case with radiators before you look into having a push-pull configuration.