Ok something a bit different. BIOS 1107. 1800x. f4-3600 c16.
I turned off fast boot, just to see what it did and got a bit of an odd result.
When I boot the machine, before the POST screen, the words "Evaluation Copy" are displayed. Perhaps to do with the 90 MHz 0003 BIOS EC hack?
I thought that was a bit bizarre.
It seems to make the RAM only run at 2133 unless I go into BIOS and change nothing, then save and restart. So its failing training.
Also getting black screen boots with the associated "line of garbage" displayed before it goes dark.
Its all quite interesting, every time I turn it on I seem to get different behaviour!
I suspect turning off fast boot has not a lot to do with any of this, its just what I did immediately prior to noticing all the weirdness.
But there is a lot of weirdness with Ryzen, particularly on the RAM front.
I'll turn fast boot back on and see if it reverts to more sensible behaviour.
The May update will fix all the weirdnesses and zenstates will spontaneously start to work again..
I live in infinite hope.