Custom-built passive water-cooled PC relies on convection chimney effect powered by triple-stacked radiators — 9800X3D build with RTX 5080 has no fans, copper, and radiator chimney, but struggles to keep temperatures down

Billet Labs built a fanless gaming PC with three stacked radiators and a chimney-style convection design, using a Ryzen 7 9800X3D and GeForce RTX 5080.

In testing with games and benchmarks like Cyberpunk 2077, Halo 3, Cinebench, and FurMark, the GPU stayed within limits but the CPU climbed to around 95 C or higher.

The Ryzen 7 9800X3D began throttling, especially when CPU and GPU loads were combined.

The project shows how far passive cooling can go — and how even a little airflow could make a big difference for modern high-power PCs.