Part 5. Is ARM Really Energy Efficient?

content by Xing Chen

I copied the first 100 systems from the June 2024 Green500 list into the following table. Then, I marked all the ARM based systems with colors: Green is for Grace-Hopper superchip as Nvidia is green, red is for A64FX as Fujitsu is red. By the way, at the same time I also marked the systems with NEC Vector Engine (accelerator) in blue, as NEC is blue, and in the “Accelerator/Co-Processor” column, I changed those systems’ status from “None”, which is wrong, to “Vector Engine”.

The fact is that Nvidia Hopper GPU itself is very energy efficient (Flops/Watt), plus that ARM CPU is also rather energy efficient, these two factors make Grace-Hopper the most energy efficient system, it occupies the head of the list. AMD Instinct GPU is also very energy efficient, it’s Instinct’s efficiency which has put those systems just behind Grace-Hopper, all with AMD CPUs. The Grace-Hopper superchip, together with the AMD Instinct GPU, form the 1st performance group, with the best power efficiency.

Because Nvidia A100 GPU is energy efficient, so all those systems with A100, no matter what is the CPU, as a performance group, occupies the 2nd position.

Fujitsu’s A64FX, the ARM based CPU is indeed energy efficient, it outperforms all the other systems with X86 CPUs, as a group, it holds the 3rd position.

NEC’s Vector Engine accelerator holds the 5th position, worse than Nvidia Tesla GPU, which is in the 4th position.

It is clear ARM is energy efficient! It’s better than X86 CPUs, even better than vector accelerators; unfortunately, it falls short of the latest version Nvidia GPUs, the GH200, the H100 and the A100!

ARM’s energy efficiency is a good news for the HPC/AI industry, as the big systems’ power consumption is reaching a not-bearable high point! This is also true with non-HPC/non-AI data centers, have you heard Google is ready to invest in modular small size nuclear generators to power their data centers?