Nvidia CPUs and GPUs dominate the bi-annual leaderboard, but FP64 performance regressions leave its long term prospectives in doubt

SC25 There's a new efficiency champ at the top of the Green500 ranking of the world's most sustainable supercomputers.

CALMIP's Kairos, located at the University of Toulouse in France, achieved an efficiency of 73.28 gigaFLOPS per watt in the High Performance Linpack (HPL) benchmark.

Since 2007, the Green500 has served as something of a counterpoint to the Top500. Rather than ranking the most powerful supercomputers by sheer performance at cost, the Green500 weighed that performance against the energy required to achieve it, measured in gigaFLOPS per watt.

This year's ranking represents another victory for Nvidia whose Grace Hopper GH200 superchips power the four most efficient machines on the Green500.

In fact, of the 10 most efficient supers in the ranking just two use AMD accelerators.