Okay guys, I have to change my tune here. I got the 500W bios to work.
My old rig was an 6700k on an msi z170a gaming m7 motherboard.
...and I was never going over 420w with the new bios.
I finally got ahold of a 5950 and I built a new rig with an MSI x570 godlike.
I benched port royal and noticed my card is now pulling between 470-490 throughout most of the bench.
So maybe this is hardware related after all?
I do have the dreaded not china/ old with red lips card. So I thought I was just in the sucky card group.
But it's running with much more stable clocks on this rig and the 500w bios is appearing to work suddenly out of the blue.