Maybe RISC-V? It's right there in the name, but I haven't really looked at it. However, there are no RISC-V chips that have anywhere near the performance x86 or ARM has, so it remains to be seen if RISC-V can be competitive with x86 or ARM for these types of things.
RISC is one of those things that sounds nice and elegant in principle, but works out rather less well in practice.