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.
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