Comment 646 for bug 1690085

The PSU problem sounds like a weak excuse from AMD or may they are talking about very very bad 10 dollars units.

The BIOS options "typical/low current" doesn't seems to change the c-states set up by the kernel routines here. With any selection, I always end up with
c0 POLL
c1 ACPI HLT
c2 ACPI IOPORT 0x414

as you can see with cpufreq cpupower idle-info or /usr/src/linux/tools/power/x86/turbostat/turbostat -n1

That happens because the firmware already informed the kernel mwait/monitor cannot be used for c-states.

If idle=halt is used, there is no c-state management and the idl instruction is used to put a core in idle mode.

I think it is the hyper treading handling that is somehow bugged, somewhere.

Also note that many ryzen users overclock their machine and if you overclock, you have to c-state problems at all.