Hi, I installed OLCP Monterey on my 2009 Mac Pro and updated the firmware to 5,1. I added a Dicasver RX 580 16GB card, which works, but macOS only shows 8MB of VRAM, causing slow performance. How can I make macOS use the full 16GB of VRAM? (The card’s BIOS hasn’t been modified).
You can try reinstalling the Web driver because macOS relies on specific drivers to interact with the hardware. So ensuring drivers are properly installed and up to date can sometimes solve VRAM recognition problems.
I think you can check the SMBIOS settings to ensure that the SMBIOS is correctly configured in your OpenCore setup, making it suitable for your Mac Pro. You may need to spoof a newer Mac model that officially supports macOS Monterey and the RX 580. For example, using the SMBIOS of an iMacPro1,1 or MacPro6,1 might improve compatibility.