What's the ULPMark (power benchmark) on any of those SiFive RISC-V chips? STM32U5 (one of the many ARM Cortex-M33 designs) is 464 ULPMark-CP.

I don't think there's even a power benchmark on any of those chips you've mentioned. At least, I'm not seeing any online in my searches.

STM32U5 (and most other Cortex-M33 based microcontrollers) are ~110nA of power consumption sleep mode, and 16uA / MHz at 160MHz, some of the most power-competitive chips I'm aware of on the market. I'm talking "run a microcontroller on a CR2032 cell for 10 years" kinda thing here.

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EDIT: Looking at the ULPMark website (https://www.eembc.org/ulpmark/ulp-cp/scores.php), it looks like the #1 chip is RSL15, which is ARM Cortex-M33, as I expected. With a ULPMark score of 1090 (higher the score, the less power the device uses). Nearly everything on the top list is Cortex-M33...

Except LP5100 and XRM32UL051 are some Chinese Chips I don't understand. They got some impressive scores but I don't know what architecture they have. Nearly everything else is Cortex-M33 (except for the Ambiq, which is ARM Cortex-M4).

Cortex-M0+ was the king of this a few years ago, but M33 has displaced it. We still see Cortex-M0+ chips due to much lower costs around though. So if RISC-V is around Cortex-M0+ level, I'd still be interested.