Quick answer
Modern AI racks pack many high-power GPUs into one cabinet, more heat than air can practically remove. The main liquid options are direct-to-chip cold plates with a PG25 or treated-water loop (most common for current GPU platforms), rear-door heat exchangers for residual air heat, and immersion in dielectric fluid.
Key takeaways
- Direct-to-chip with a CDU is the mainstream route for current GPU racks.
- Fluid choice follows the hardware maker’s qualification (e.g. NVIDIA DSX Ready lists).
- Plan fluid supply, fill volume and testing with the CDU.
General information. Confirm the exact fluid, equipment and qualification with your hardware or CDU supplier before specifying.
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The options
| Approach | Coolant | Read more |
|---|---|---|
| Direct-to-chip (cold plates) | PG25 or treated water in a closed loop | Cold plates · PG25 |
| Rear-door heat exchanger | Facility or CDU water | RDHx |
| Single-phase immersion | Hydrocarbon or ester dielectric | Dielectric fluids |
| Two-phase immersion | Engineered low-boiling fluid | Single vs two-phase |
The cooling stack for a direct-to-chip AI row
- Cold plates on GPUs and CPUs, connected by quick disconnects.
- Rack manifolds.
- CDU (in-rack, in-row or centralised).
- Facility water to dry coolers, towers or chillers.
- Air or RDHx for the remaining heat.
Getting the fluid right
- Use fluids qualified for your platform; see the NVIDIA DSX Ready coolant list.
- Calculate the fill volume including CDU, manifolds and piping, plus top-up stock.
- Agree who samples and tests the fluid, and how often. See CDU coolant maintenance.
Who you will work with
Server maker or integrator, CDU manufacturer, fluid supplier, mechanical contractor, and a water-treatment or fluid-testing service.
Free: liquid-cooling fluid RFQ checklist
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Get the checklist →Frequently asked questions
Why do AI racks need liquid cooling?
Dense GPU racks produce more heat than air cooling can practically remove; liquid carries heat far more effectively.
What coolant do AI GPU racks use?
Most direct-to-chip deployments use an inhibited propylene glycol mix such as PG25 or a treated water fluid qualified by the hardware maker.
How we source this page
- Facts come from manufacturer pages, datasheets, owner's manuals and standards bodies, linked under Sources.
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