Workaround for KB5124008 causing my discrete GPU (add-in Nvidia 4070 card) to stop displaying

tysonflint 1 Reputation point
2026-09-13T04:10:48.1333333+00:00

I just installed KB5124008 about two days ago, and I've just started having trouble with my HDMI signal. I've had to unplug my HDMI cable a few times from the GPU and plug it back in to restore video. The issue became worse until I could no longer get any signal on the monitor. I had to RDP into the PC from another device to troubleshoot. It appears that the video flipped away from my discrete Nvidia 4070 add-in card, and started displaying on the 7950X3D CPU's integrated AMD Radeons HDMI connector on the motherboard. I was able to resolve this issue by changing this registry key:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity]

"Enabled"=dword:00000000

The default was:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity]

"Enabled"=dword:00000001

After changing from "Enabled"=dword:00000001 to "Enabled"=dword:00000000 followed by a reboot, my Nvidia 4070 GPU was able to display video again without issue. I know this likely opens up some security concerns, so am hoping to find out if this is a known issue.

In my troubleshooting, I tried updating my Nvidia 4070 from version 610.88 (game ready) to 616.92 (game ready). This didn't help the issue. I reverted back to 610.88, rebooted, same issue. Changed the above registry value to "Enabled"=dword:00000000, moved the HDMI cable back to the 4070, rebooted again, and got working video again.

BIOS version considerations: My motherboard is a Gigabyte X670 AORUS ELITE AX (revision 1.2). I already had "Settings" / "IO Ports" / "Initial Display Output" set to "PCIe 1 Slot". I didn't have the option to disable the integrated graphics in my F37e BIOS, so after fixing the issue with the registry change, I upgraded my BIOS to F42d. A new option appeared that allowed me to disable the integrated graphics completely. I've currently disabled the onboard integrated graphics, but have not yet re-enabled HypervisorEnforcedCodeIntegrity by setting it back to 00000001. I going to give it a few days to see if I have any more issues before re-enabling it. I'm posting this information in case anyone else has this issue, hoping to help others, or perhaps find a better solution.

Windows for home | Windows 11 | Windows update
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Answer accepted by question author
Kai-H 26,580 Reputation points Microsoft External Staff Moderator
2026-09-13T09:11:30.2666667+00:00

Hi, tysonflint

This does look like a possible HVCI/graphics-driver compatibility problem, but I could not verify that the RTX 4070 display failure is currently listed as a confirmed known issue for KB5124008. Memory Integrity, also called HVCI, can block incompatible low-level drivers, so disabling it may restore functionality but reduces protection.

Here are some suggestions you can try:

Keep the monitor connected to the RTX 4070 and leave Initial Display Output set to PCIe 1 Slot. Disabling the integrated GPU is reasonable for testing, but note the original BIOS setting in case you need to restore it.

Re-enable Memory Integrity through Windows Security > Device security > Core isolation details, then restart. Avoid leaving the registry workaround disabled permanently unless necessary.

If the black screen returns, install the latest NVIDIA driver using the installer’s Custom installation > Perform a clean installation option. Updated display drivers are the preferred fix for HVCI compatibility issues.

If it still fails, temporarily uninstall KB5124008 from Settings > Windows Update > Update history > Uninstall updates, then pause updates briefly and report the issue through Feedback Hub.

Keep the new BIOS installed unless Gigabyte advises otherwise.

Thank you for your patience in reading, I hope this information has been helpful to you. 

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  1. tysonflint 1 Reputation point
    2026-09-15T20:21:05.5133333+00:00

    Thank you @Kai-H for getting back to me on this. I re-enabled Memory Integrity / HVCI with [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\DeviceGuard\Scenarios\HypervisorEnforcedCodeIntegrity]

    "Enabled"=dword:00000001 Then I rebooted. The video output remained successfully on the Nvidia 4070 add-on card's HDMI port. I believe the fix here was to disable the motherboard's AMD Radeon GPU in the BIOS, which only became available once I upgraded my Gigabyte X670 AORUS ELITE AX (revision 1.2) BIOS from F37e to F42d.

    Thanks for encouraging me to try re-testing with strengthened security after the updated BIOS tweak.

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