Innovative London-based PC cooling firm Billet Labs is back with another water-cooled system, this time aiming for a completely passive, fanless build. The video below explains why this interesting build was conceptualized, how it was built, its benefits and drawbacks, and how it performs, all with an eye on thermals.

Felix from Billet Labs starts the video presentation standing next to another of the firm's special projects – Walley. This machine is wall-mounted and shows plenty of Billet Labs signature flair. Its multiple powerful fans can get rather noisy when the system is under duress, though. If the fan speeds are scaled back, things start to get uncomfortably warm. The new custom build, therefore, targets a gaming PC that is much quieter.

Regular readers may be familiar with Billet and founder Felix on YouTube, most recently for ‘Raddy,’ the Victorian radiator PC. However, Raddy proved to be a bit noisy for a living room gaming machine, and it included some fans, so its performance components are being reused here.

Felix reveals that the hulking cast-iron radiator cooled beast known as Raddy wasn’t silent due to cavitation bubbles in the pump, which necessitates radiator flushing once a week. Not a trivial task. Also, Raddy wasn’t a fully passive design as it incorporated fans.

So, the new PC and Raddy share a lot of the same components, particularly the performance parts like an AMD Ryzen 7 9800X3D processor, an Nvidia GeForce RTX 5080, and an Aorus Pro B850 motherboard.

The new build used a trio of radiators in different sizes, ranging from large to very large. They were arranged above the heat-generating components, taking advantage of what Felix describes as a convection chimney effect.

For about the next 30 minutes of the video, we get to witness the skills behind the Billet Labs build process. The main stages roughly consisted of building the platform (based on an 8mm aluminum plate), mounting the PC parts, adding cooling, and then plumbing. From about 33 minutes in, we get to see the new living room gaming PC fire up Windows 11 for the ‘first time,’ and performance / thermal testing commences.

Felix isn’t satisfied with the silence of the building at first. So he had to turn off the motherboard fan and also adjust the pump speed to 80%. The machine was then tested until temperatures began to level off, over various workloads. Testing began with idling for half an hour, playing Peggle for a while, and then running Cinebench for half an hour. Things got serious as Halo 3 was fired up for a session. In the real gaming tests (Halo 3, Expedition 33, Cyberpunk 2077), the GPU never thermal throttled, but the CPU would a little as it hit 95 °C or more.

More stress testing was initiated, culminating in running Cinebench and FurMark simultaneously. This pulled over 450W of power and brought the radiator water temps up to 60C+, which is the maximum rated level for the pump. A throttling CPU was observed again in these tests. A full table of tests, power output, and temperatures is shared in the Reddit post embedded below.

Fan-less gaming PC - 5080/9800x3d/32gb/2tb - Yes I’ll probably add fans next from r/pcmasterrace

In conclusion, Felix reckons passive water cooling alone isn’t really enough for a powerful modern gaming rig. Even a single case fan would probably be enough to make a world of difference. So, stay tuned for a follow-up video where you can see how the same Billet Labs PC performs with a 120mm fan atop, pulling air upwards, accelerating that chimney effect.

Follow Tom's Hardware on Google News, or add us as a preferred source, to get our latest news, analysis, & reviews in your feeds.

Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.