When I first built my current PC with the Ryzen 9 5900X, I bought the Aorus 360mm AIO to keep the CPU temperatures in check, no matter what I threw at it. At the time, it seemed necessary for a 12-core CPU. When I later switched to the 8-core 5800X3D, I already had more than enough thermal headroom, so I didn't think twice about keeping it. Even though it ran a bit hotter than my old 5900X, it never crossed 80C while gaming, so I never felt the need to pay full price for another AIO.

Unfortunately, everything changed when my AIO suddenly died due to a pump failure. At that point, I just needed a quick and cheap replacement to keep my PC usable until I moved to AM5 in a few months, so I picked up the Arctic Freezer 36 for $30 as a stopgap. I expected it to be a clear downgrade from my 360mm AIO, but surprisingly enough, my CPU temperatures were mostly the same. I'm not saying my AIO wasn't doing its job, but it made me question how much cooling I actually needed in the first place.

My CPU was using whatever thermal headroom it had

My 360mm AIO just gave it more headroom to boost higher

One thing I didn't fully understand before this switch was how modern CPUs actually behave under load. I always assumed that a better cooler would simply lower temperatures across the board, but that's not really how it works anymore. A CPU like my 5800X3D is constantly adjusting itself based on the thermal headroom available. So, if there's more headroom from using a high-end 360mm AIO, it doesn't just sit there running cooler. Instead, it uses that to boost a bit higher and sustain those clocks more consistently under load.

That’s exactly why my temperatures didn't change as much as I expected when I switched to the Freezer 36. I no longer had the same thermal headroom, but my CPU adjusted accordingly to stay within its safe operating range. And since I was mostly gaming instead of running heavy all-core workloads, I wasn't really pushing the limits of either cooler in the first place, which is why the real-world difference ended up being so small. For the way I used my PC, my cooler just wasn't a major limiting factor.

My case airflow was already doing most of the work

My airflow setup and Kryonaut Extreme thermal paste helped close the gap

When I had the Aorus 360 AIO, I didn't realize how much my Phanteks P500A case was already helping with my CPU temperatures. It's a high-airflow case by design, and I have already set it up with a proper front-to-back airflow path and enough intake to maintain slight positive pressure. That meant my components were constantly getting fresh air, which naturally kept temperatures in check before the cooler even had to do its job. When your airflow is dialed in like that, the cooler doesn't have to work as hard to keep your CPU relatively cool.

As a result, when I switched to the Arctic Freezer 36, I wasn't starting from a worse baseline. Sure, using a single tower air cooler meant that it had to naturally work harder, but it didn't have to deal with heat buildup inside the case. On top of that, I used Thermal Grizzly Kryonaut Extreme to make up for the weaker cooling performance of an air cooler. All of that combined meant the real-world performance difference between my 360mm AIO and a budget air cooler ended up being much smaller than I expected.

High-end AIOs still make sense for sustained workloads

But you can get away with an air cooler if you're not chasing peak clocks

I'm not going to act like I'm planning to stick with this air cooler in the long term. There's a reason high-end AIOs exist, and in the right scenarios, they're still the superior choice. Ideally, I want my CPU to maintain its peak boost clocks for as long as possible without worrying about thermal headroom. With the Freezer 36, I didn't quite get the same peak boost clocks I was used to seeing with the Aorus 360. That's where a high-end AIO can make a difference, especially in sustained workloads where temperatures can slowly creep up and start limiting performance.

That said, if you don't mind giving up a bit of that peak boost behavior, you'll be perfectly fine with an air cooler, especially a dual-tower option like the Thermalright Peerless Assassin 120. In most gaming scenarios, that difference doesn't really translate into something you can actually feel. Your CPU may run a couple of degrees warmer, but it will continue to operate within its safe temperature limits, and your frame rates will remain largely unchanged.

This showed me I'm chasing diminishing returns with AIOs

If there's anything I learned from this switch, it's that I was getting less in return for the price I paid for my 360mm AIO. Sure, my CPU used to maintain higher boost clocks, but that didn't mean my gaming performance took a hit the moment I switched to a budget air cooler. In most cases, I was already getting the performance that mattered, and the extra cooling headroom was just giving me slightly better numbers on paper and a bit more peace of mind. For how I actually use my PC, the premium I paid was more about peace of mind than noticeable performance gains.