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

Dropbox engineers used Hack Week 2025 to build a liquid-cooling system for GPU servers, anticipating the rising heat and power demands of AI workloads. Their prototype, assembled from radiators, fans, a pump, reservoir, tubing, manifolds, and sensors, reduced temperatures by 20–30°C during stress tests compared with air cooling. The project also enabled quieter operation and may help Dropbox use less data-center space and energy as GPU requirements increase.

Building a Custom Liquid-Cooling System

• The team built the system from scratch after failing to source a complete commercial setup in time.
• It replicated key data-center cooling components:
  • Radiators and fans for heat dissipation
  • A pump and reservoir to circulate coolant
  • Tubing and manifolds
  • Sensors to verify flow and monitor performance
• Engineers tested the cooling loop before connecting expensive GPUs, then integrated it with a GPU server.

Thermal and Noise Improvements

• Liquid cooling lowered CPU and GPU temperatures by approximately 20–30°C during demanding torture tests.
• Because the liquid loop handled the primary heat-generating components, the team could:
  • Remove some fans
  • Run others at lower speeds
  • Reduce noise and potentially power consumption
• Remaining airflow was directed toward lower-heat components such as DIMMs and network cards.
• The team considered using an airflow baffle to cool those components more precisely.

Preparing for AI-Era Infrastructure

• High-end GPUs increasingly consume more power and generate more heat, potentially making air cooling insufficient.
• Liquid cooling could allow Dropbox to:
  • Fit more powerful servers into existing data-center footprints
  • Avoid spreading servers across additional space
  • Reduce cooling energy and operating costs
• Although vendors do not yet universally require liquid cooling for top-tier GPUs, the engineers expect that requirement to become more common.
• Dropbox’s growing focus on AI workloads provided additional motivation to investigate the technology early.

Hack Week as an Experimentation Platform

• The project received funding and organizational support from Dropbox’s infrastructure teams.
• Hack Week gave engineers time to explore a long-term infrastructure problem outside their normal work.
• The team’s Learn Fast award recognized the project’s emphasis on experimentation and rapid learning.
• Working in person helped the engineers exchange ideas, troubleshoot quickly, and collaborate with colleagues across the company.

Dropbox plans to expand testing with additional liquid-cooling labs in multiple data centers. The prototype is an early step toward infrastructure capable of supporting increasingly powerful, GPU-intensive AI systems.