Hack Week 2025: How these engineers liquid-cooled a GPU server

Dropbox engineers built a custom liquid cooling system for GPU servers during Hack Week 2025, winning the Learn Fast award for accelerating innovation in infrastructure.

• •The team assembled the system from scratch using radiators, pumps, reservoirs, tubing, manifolds, and sensors instead of a pre-built unit
• •Liquid cooling achieved 20–30°C lower operating temperatures under heavy stress tests compared to existing air-cooled production systems
• •Removing or slowing fans became possible since liquid cooling handled CPUs and GPUs directly, with minimal airflow still needed for DIMMs and network cards
• •The project is forward-looking: as next-gen GPU servers consume more power, air cooling may only support mid-range hardware, making liquid cooling infrastructure essential
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