I got readings like this a couple of weeks ago
Motherboard software showed the same fluctuations.
Broke out the DMM and checked on a peripheral connector, it showed OCCT to be incorrect.
Attempted to backprobe the 24 pin connector and the system shutdown.
Turns out it had somehow loosened and was causing the funky voltage readings.
Reconnected it and everything went back to normal.
Make sure the 24 pin connection is tight.