@hooddy Try this: Z9PED8WS_Complete.rar (3.5 MB)
This is based from bios 5802, added nvme booting capability along with rebar capability (to enable rebar, you can refer to this post). You can try to clean install W11 with CSM Disabled + Above 4G Decoding enabled in bios.
Additionally, Above 4G Decoding should function normally now, you can confirm by checking Device Manager → View → resource by type → Large Memory, it should be similiar to this:
(image credit to @Vlad0)