Der8auer Built a CPU Cooler Chimney to Prove Vertical Cooling Makes Sense
The old advice that building your PC like a chimney, with hot air rising and fans helping it along the way, does make sense and does have a real effect on cooling. Just not as much as most DIY enthusiasts think. To prove it, famed overclocker Roman “Der8auer” Hartung built a meter-tall CPU cooling tower, taking readings at different heights, and it turns out you need quite a lot of chimney to have a decent effect.
The chimney effect is more than just convection sending hot air upwards. The idea is that by trapping the air within a vertical flue, the chimney pulls in cooler air from underneath, thereby accelerating cooling potential as well as helping to exhaust the heat. The idea is that with enough of a case delivering this effect, the cooling capacity of the system is improved.
But how big a chimney do you need for this to actually work? To figure it out, Dera8er built a system with a 240mm AIO without fans connected to a 9800X3D pinned at 100W load, so the coolant temperature would remain consistent. He then attached a chimney to the AIO and recorded the temperatures. Did the chimney pull more cool air through the AIO than convection of the ambient air alone?
Adding just 20cm of chimney to the top of the AIO had a noticeable effect – it dropped coolant temperatures by up to five degrees over the next half an hour, despite consistent room temperatures. But what about more than that?
Adding more sections to the 3D printed PLA chimney, Der8auer brought the height to 80cm, almost hitting the ceiling. The coolant temps fell by an additional five degrees almost immediately, and a further five degrees over the ensuing five minutes.
The end result saw a near-20 degree drop in the CPU’s peak temperatures, showcasing just how effective a chimney can be – particularly in passive scenarios. Fans can generate the same effect with a little electricity and a lot less space, so are still preferable, but if you’ve been working on a passive gaming PC idea, maybe incorporating a big tower in the design is the way to go.
