I bought an H170i 420mm AIO and installed it in a Fractal Design North XL after upgrading my system in 2024. The radiator would not fit at the top, so I mounted it in the front and moved the fans to the top as exhaust. Since the front radiator blocks much of the intake airflow, the case feels hot, especially around the RTX 5090, and the tempered-glass side panel gets very warm. My room also heats up noticeably during heavy simulator use. I recently bought another full-size tower based on an AI recommendation, but the 420mm radiator would not fit there either, even in the front. I am returning that case and deciding whether to find a case with proper 420mm support or replace the AIO with a 360mm model. The CPU is a Ryzen 9 7900X3D. What would be the best approach for improving airflow and GPU temperatures?
5 Answers
The Meshify 2 XL is worth considering. It supports a 420mm radiator at the top, has a lot of internal space, and can accommodate plenty of fans, including bottom intake fans. That extra airflow could be useful for a power-hungry RTX 5090.
I would consider changing the cooler rather than replacing the case. A 360mm AIO mounted at the top, with intake fans at the front, would give the RTX 5090 access to cooler air. A 7900X3D generally does not require an enormous cooler, so a quality 360mm model should be sufficient unless you have unusually high CPU power limits or workloads.
A few cases that may support a 420mm unit include the Antec Flux Pro, Lian Li Lancool III, Meshify 2 XL, and Phanteks NV9. Check the radiator position carefully on the manufacturer's specifications, though—some cases support 420mm only in the front, while others support it at the top. Compatibility databases are useful for narrowing the list, but the case manual or product page should be the final check.
Keep in mind that better airflow will not make the room cooler. The heat in the room is determined mainly by how much electrical power the system uses. An RTX 5090 can draw hundreds of watts by itself, and nearly all of that power eventually becomes heat. Better airflow may lower component temperatures, but it can also move that heat into the room more efficiently. A cooler or larger case cannot remove the heat from the room without exhausting it elsewhere.
Before replacing everything, check actual temperatures and fan behavior. Make sure the front radiator fans are configured as intake, the top fans are exhausting, and consider adding bottom intake fans if the case supports them. You may also need more aggressive fan curves. Compare CPU, GPU, hotspot, and internal case temperatures against room temperature. If the GPU is not approaching its thermal limit, the warm glass may simply be normal for a high-power card in a compact airflow path.
That makes sense. The CPU is a Ryzen 9 7900X3D, so I was wondering whether stepping down to a good 360mm AIO would be reasonable.