I don't think it's a matter of one or the other but rather using different ISAs for different things. All the RISC-V use by NVidia seems to have been in microc

I don't think it's a matter of one or the other but rather using different ISAs for different things. All the RISC-V use by NVidia seems to have been in microcontrollers and all the recent ARM use has been in application cores.