In the Green500 the systems of the TOP500 are ranked by how much computational performance they deliver on the HPL benchmark per Watt of electrical power consumed. This electrical power efficiency is measured in Gigaflops/Watt. This ranking is not driven by the size of a system but by its technology, and the ranking order looks therefore very different from the TOP500. The computational efficiency of a system tends to slightly decrease with system size, which among technologically identical systems gives smaller systems the advantage.
This edition of the Green500 sees three systems with identical architecture in the top 3 positions. They are all BullSequana XH3000 systems using the Grace Hopper Superchip 72C 3GHz, NVIDIA GH200 Superchip, and Quad-Rail NVIDIA InfiniBand NDR200. All three systems debuted on the previous Green500 list six months ago, and the order among them is unchanged this edition.
KAIROS, a BullSequana XH3000 system at the CALMIP / University of Toulouse – CNRS center, retains the No. 1 spot on the Green500 with an energy efficiency of 73.28 Gigaflops/Watt. It achieved 3.046 Petaflop/s on the HPL benchmark. The system uses the Grace Hopper Superchip 72C 3GHz, NVIDIA GH200 Superchip, and Quad-Rail NVIDIA InfiniBand NDR200.
ROMEO-2025 holds the No. 2 spot, as it did last edition. The system is installed at the ROMEO HPC Center - Champagne-Ardenne in France and has 47,328 total cores. With an HPL benchmark of 9.863 Petaflop/s, it achieved an efficiency of 70.91 Gigaflops/Watt. The architecture is identical to the No. 1 system KAIROS; ROMEO-2025 is substantially larger, which results in its energy efficiency being slightly lower.
The Levante GPU extension system at DKRZ - Deutsches Klimarechenzentrum in Germany again holds the No. 3 spot. It also has an identical architecture to the No. 1 and No. 2 systems and achieved 6.747 Petaflop/s HPL performance and an efficiency of 69.43 Gigaflops/Watt.
