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Windows 11 fails to start when 4G decoding is enabled.

Windows 11 fails to start when 4G decoding is enabled.

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Hockeybeast87
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138
08-01-2021, 04:57 AM
#1
Need the boot settings activated for dual booting Mac OS with OpenCore. Windows keeps freezing on the spinning dots without any issues. I’m unsure how to enable verbose boot or access logs from the registry changes. I found a log file from the Startup repair tool attached—maybe it helps. Thanks, m9x3mos.
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H
Hockeybeast87
08-01-2021, 04:57 AM #1

Need the boot settings activated for dual booting Mac OS with OpenCore. Windows keeps freezing on the spinning dots without any issues. I’m unsure how to enable verbose boot or access logs from the registry changes. I found a log file from the Startup repair tool attached—maybe it helps. Thanks, m9x3mos.

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BMW1313
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08-08-2021, 04:41 PM
#2
It appears the system was set up as a legacy version without UEFI. Enabling that causes CSM to be disabled. Try using the Windows USB installer to start a boot and see if repairs are possible.
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BMW1313
08-08-2021, 04:41 PM #2

It appears the system was set up as a legacy version without UEFI. Enabling that causes CSM to be disabled. Try using the Windows USB installer to start a boot and see if repairs are possible.

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Srui
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08-08-2021, 06:41 PM
#3
Hello, the device was set up without CSM enabled and is working properly with both 4G+ decoding and CSM disabled. It still doesn’t load when decoding is turned on. I’ll check the USB installer now.
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S
Srui
08-08-2021, 06:41 PM #3

Hello, the device was set up without CSM enabled and is working properly with both 4G+ decoding and CSM disabled. It still doesn’t load when decoding is turned on. I’ll check the USB installer now.

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JEFF_JEFFERSON
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627
08-09-2021, 03:33 AM
#4
It's also likely the device uses MBR rather than GPT. It may require GPT to function properly.
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JEFF_JEFFERSON
08-09-2021, 03:33 AM #4

It's also likely the device uses MBR rather than GPT. It may require GPT to function properly.

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_Lolikc_
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184
08-14-2021, 01:56 AM
#5
UEFI settings prevent Windows 11 from installing on MBR drives
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_Lolikc_
08-14-2021, 01:56 AM #5

UEFI settings prevent Windows 11 from installing on MBR drives

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Charoonia
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134
08-14-2021, 02:10 AM
#6
It's good to hear. Just a quick note—never double-checked mine, but I recall it being true.
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C
Charoonia
08-14-2021, 02:10 AM #6

It's good to hear. Just a quick note—never double-checked mine, but I recall it being true.

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lalacraft1
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08-14-2021, 07:50 AM
#7
I think I fixed the problem by including the npci=0x2000 option in my OpenCore setup, which lets me proceed without needing 4G+ decoding. It's more of a temporary fix than a permanent solution, but I'm sharing it in case someone else faces the same issue.
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lalacraft1
08-14-2021, 07:50 AM #7

I think I fixed the problem by including the npci=0x2000 option in my OpenCore setup, which lets me proceed without needing 4G+ decoding. It's more of a temporary fix than a permanent solution, but I'm sharing it in case someone else faces the same issue.

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Lalesita
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50
08-14-2021, 09:20 AM
#8
This discussion is quite engaging. I'm also setting up a dual-boot configuration with a Ryzen 7 2700x and an ASRock b450 Pro4 board. I'm running OpenCore as my boot manager and recently moved from version 0.6.2 to 0.7.8 (I tend to stick with the same setup). My graphics card is an XFX RX 5500 XT with 8GB of VRAM, which was added fairly recently. I've noticed that keeping CSM off but enabling high-speed decoding allows my clean OpenCore/MacOS experience to launch smoothly, whereas my old Windows 11 drive keeps failing to boot. Notably, with 4G decoding active, USB drives and some PCI devices like my NVMe storage stop working during startup. This seems to be bypassing OpenCore entirely, letting me manually select a boot device via F11. What appears to be happening is that the system boots but then shuts down USB ports and other peripherals. If I turn off 4G decoding, everything boots without issues. To be clear, my Windows 11 is mounted as a GPT partition. For now, this troubleshooting will likely stop because I rarely switch between OSes on my dual-boot setup.
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L
Lalesita
08-14-2021, 09:20 AM #8

This discussion is quite engaging. I'm also setting up a dual-boot configuration with a Ryzen 7 2700x and an ASRock b450 Pro4 board. I'm running OpenCore as my boot manager and recently moved from version 0.6.2 to 0.7.8 (I tend to stick with the same setup). My graphics card is an XFX RX 5500 XT with 8GB of VRAM, which was added fairly recently. I've noticed that keeping CSM off but enabling high-speed decoding allows my clean OpenCore/MacOS experience to launch smoothly, whereas my old Windows 11 drive keeps failing to boot. Notably, with 4G decoding active, USB drives and some PCI devices like my NVMe storage stop working during startup. This seems to be bypassing OpenCore entirely, letting me manually select a boot device via F11. What appears to be happening is that the system boots but then shuts down USB ports and other peripherals. If I turn off 4G decoding, everything boots without issues. To be clear, my Windows 11 is mounted as a GPT partition. For now, this troubleshooting will likely stop because I rarely switch between OSes on my dual-boot setup.

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jpc2002
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08-17-2021, 11:57 PM
#9
I can verify that for my ASRock b450 Pro4, resetting the BIOS to defaults, turning off CSM and activating Above 4G Decoding prevents booting from a bootable USB created with the Create Media Windows 11 tool. When all settings remain the same but only Above 4G Decoding is disabled, all drives, including the USB, boot correctly. I understand my current Windows drive probably needs a fresh install, but I’m confused why a standard boot USB isn’t sufficient.
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jpc2002
08-17-2021, 11:57 PM #9

I can verify that for my ASRock b450 Pro4, resetting the BIOS to defaults, turning off CSM and activating Above 4G Decoding prevents booting from a bootable USB created with the Create Media Windows 11 tool. When all settings remain the same but only Above 4G Decoding is disabled, all drives, including the USB, boot correctly. I understand my current Windows drive probably needs a fresh install, but I’m confused why a standard boot USB isn’t sufficient.

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