Hello,
Clear the UEFI using the rear IO panel button, do not apply any overclocking (including XMP or memory overclock), and see if the problem persists.
If issue continues:
Go to the start menu, type in Event Viewer then go to Windows Logs > System. After the problem occurs check the log and report back. It sounds as if the display driver is crashing and restarting. Ensure the latest graphics card drivers are installed.
Note: if using a PCIE riser for the GPU, remove riser and test GPU connected directly to the motherboard.
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090