This completely submersible RTX 4090 PC is slightly silly but totally awesome

pcgamer.com:

You can always rely on YouTuber DIY Perks to go the extra yard. Or should that be fathom? This time, he's built a fully submersible PC running cutting-edge hardware, including an RTX 4090 GPU and Intel Raptor Lake processor.

The basic idea here is that submerging things in water makes for excellent heat dissipation. Which is why IT companies are playing with sticking data centres in the sea.

Anyway, as ever the engineering and attention to detail in the build is top notch. The core of the build is an acrylic cylinder. The immediately contradicts the core cooling remit as acrylic is a very poor conductor of heat.

The solution is a very steam-punk looking arrangement of external copper pipes plumbed into the PC's internal water cooling setup. The pipes enter and exit the cylinder through end caps. Those are also made from copper in order that the pipe to end cap interfaces can be neatly soldered and made totally water tight.

There's a gasket between each end cap and the cylinder. Cleverly, the two end caps  are connected together via external rods which allow the caps to be pulled towards each other, clamping the gaskets and creating a tight seal.

The required cabling enters via another copper pipe on the upper cap, the top of which sits above the water surface, preventing the need to make a tricky water-tight seal for the cables.

DIY Perks then chucked the whole thing in his surprisingly deep (two metres) garden pond. Barring a minor buoyancy miscalculation it all went, well, swimmingly.

The temperature of the coolant only went up by a couple of degrees under sustained load, while the CPU never hit more than 60 degrees C and the GPU topped out in the low 40s.

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