Problems with PCI-E at boot - ncpi boot arg fix?


New member
AMD OS X Member
Sep 5, 2020
Here's a parts list for any hardware compatibility concerns:

So basically my install of OpenCore (Catalina 10.15.6) went relatively smoothly all things considered. The only issue that I'm having is that I must have "Above4GDecoding" enabled in my BIOS in order for OpenCore to boot, otherwise the bootloader gets stuck at PCI-E. This isn't an issue on it's own, however it does become a problem since on a separate boot drive I have a Windows 10 installation (MacOS is on the Samsung SSD, Windows is on the WD SSD.), and Windows refuses to boot when "Above4GDecoding" is enabled - I've tried the GPT partition scheme to circumvent this but no dice.

Essentially, every time I boot I have preemptively change the "Above4GDecoding" setting in the BIOS before deciding which OS I want to boot into. I've read on different threads and in forums that adding the ncpi boot arg can allow you to boot without "Above4GDecoding" (or maybe it helps the bootloader get past the PCI-E problem), but I have already installed MacOS successfully.

So my first question is, can I have the ncpi boot arg in place of "Above4GDecoding" in order to boot into MacOS? Does this boot arg solve the bootloader getting stuck at PCI-E?

If so, second question being how do I add/enable this boot arg now that I have already installed MacOS?

Apologies if this is a little long winded, just looking to provide as much info as possible. Thanks <3
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