Host Fabian Alefeld interviews Professor PS Lee, Head of National University of Singapore Mechanical Engineering & Program Director of STDCT, and founder of CoolestDC, about heat as a key constraint in AI infrastructure as data centers shift from CPU-heavy to GPU-dense systems with higher power density, hotspots, and bursty workloads. Lee explains why cooling must be treated as an integrated “chip to grid” system spanning cold plates, racks, CDUs, piping, controls, and operations, and discusses single-phase versus two-phase direct-to-chip liquid cooling and the added need for condensation in closed loops.

Professor Lee describes how additive manufacturing (AM) enables complex fin structures and unibody cold plates that reduce leakage risk, lower junction temperatures (~10°C), cut pumping power (60–70%+), and reduce material use, while requiring TCO evaluation. At NUS’s live testbed (22 liquid-cooled racks, ~500 kW), AM cold plates are being deployed and show promising thermal, power, and compute-performance improvements; future work includes two-phase cooling and broader system-level heat rejection, warm-water operation, and waste-heat reuse, plus a discussion of challenges and potential AM roles in space-based data centers.

02:13 Meet Professor Lee

05:26 Chip To Grid Cooling

10:22 Liquid Cooling Maturity

14:15 Two Phase Explained

18:12 Cold Plate Tradeoffs

20:40 AM Unibody Cold Plates

24:41 Benchmarking AM Gains

30:18 AM For CDUs

34:13 Inside STDC Testbed

38:09 Reliability And Leakage

39:00 Next Phase Roadmap

42:31 Orbital Data Centers