Asrock Rack x470D4U Resizable bar

To my surprise they answered a day later with a BIOS update:

We add resized bar option in BIOS L4.27
Advanced -> PCI Subsystem Settings -> Re-Size BAR support.

The BIOS is not listed on Asrocks pages yet, so you should probably not use it yet. (Especially not since you got the file from a random guys blog).

But if somebody needs it, here's the file.

X47D4U427.ZIP (10 MB)

Other names for resizable bar:

• CAM - Clever Access Memory
• SAM - Smart Access Memory
• Rebar - Resizable bar