AI-GPU coolers made with Rheocasting

Efficient cooling is defined by one thing above all: how quickly and reliably it moves heat away from fragile electronics. In AI data centers, the amount of electrical power, which later turns into heat, needed to feed such AI clusters is massive.

A water-cooled 4U-rackmount Server typically contains 8 GPUs, each ranging from 300 to 1200 W, plus two CPUs, each between 350 and 500 W. Not counting the network cards and storage, which provide up to 10,600 Watts of heat transfer. A typical rack contains 8 of these servers, along with networking components. From the key components come 84.800 Watts of heat on maybe two square meters. And the number of racks is only limited by the power source and cooling capability.

This AI expansion is happening at an extraordinary speed. Independent analysts size the AI server market at ~$125–143 billion in 2024, projecting ~$840–855 billion by 2030. That is a compound growth rate in the mid-30s to high-30s. Underneath that, data-centre capex is forecast to reach ~$1.2 trillion by 2029, with AI servers taking a dominant share, while construction spend on U.S. data-centres hit record highs in mid-2025, driven by AI demand.

Copper for Cooling?

Copper is the benchmark for heat conduction of around 390–401 W/m·K at room temperature, and for years cold plates have been machined from copper and then vacuum-brazed to seal their internal channels. Those methods deliver excellent performance, but they are process-intensive and expensive by design: two plates are CNC-milled with micro-structures, assembled with filler, and brazed in vacuum, then pressure- and leak-tested.

However, the long and expensive manufacturing chain (CNC + brazing) and ongoing corrosion risks are significant operational costs, particularly given that a single GPU can cost upwards of 6 figures.

Aluminium comes in where Copper can’t compete

Aluminium offers a different route, provided you respect the physics. Pure aluminium conducts heat well (~220–237 W/m·K). Still, standard high-pressure die-cast (HPDC) alloys rely on 9 to 12 % Si for castability, and silicon in aluminium is a strong barrier to heat flow. That is why typical die-cast heat-sink alloys sit near 100 to 130 W/m·K and struggle to move the required heat into the cooling channels or fins. Every foreign atom, each grain boundary, and each second phase scatters electrons (and phonons), lowering thermal conductivity.

The way forward is to lower the silicon in aluminium alloys, while keeping the casting leak-free, which is exactly what Rheocasting does. In high-solid-fraction Rheocasting, the castability is not defined by the silicon content.

By using Rheocasting, the cold plate housing is cast within seconds, rather than being milled from billet. This approach also eliminates countless hours of expensive CNC time. That’s a manufacturing cost win before you even reach the materials line on the bill of materials. Through mid-September 2025, LME cash copper has traded near $10,000/t, while aluminium sits around $2,600–2,700/t. When your cold plates and manifolds are kilograms of metal, the delta multiplies across programmes and spares. The light-weight cooling solution also saves weight in the server racks and data centers, which is crucial when you add multiple floors of racks.

Reliability arguments lean the same way. Copper is widely used for cold plates, but it also emphasises that all wetted materials must be compatible and that corrosion depends on chemistry and flow velocity inside micro-channels. Mixing copper with brass, aluminium, or steel invites galvanic couples; copper itself can suffer velocity-assisted erosion-corrosion in high-purity water loops. Keeping the wetted path homogeneous simplifies life, but only the aluminium route lets you cast the complex geometry directly.

Conclusion

Pulling the threads together: copper remains the highest-conductivity industrial metal in use, but in the real world of AI racks, it typically arrives as a machined assembly that demands vigilant corrosion management across mixed-metal loops.

Rheocasting with low-Si aluminium alloys enables direct casting of the cold-plate housing and fin core, delivering ~180–190 W/m·K conductivity in a leak-tight part. This is achieved with a raw material price a fraction of copper, and without the same galvanic corrosion pitfalls.

This is an excellent opportunity for foundries to capitalize on an exploding worldwide trend that shows no signs of slowing down. Develop this business opportunity outside automotive for your foundry by using the Rheocasting Expert on Demand from Casting-Campus GmbH. Schedule a Free Consultation Call below to inquire more insights.