PC stuck in Boot to BIOS-Loop

[Ratisbona]

Hello everyone,
I booted up my gaming-PC yesterday after work and it worked perfectly fine, like everyday for the last few years. I then left the room for a while, and when I came back it showed the BIOS Screen.
No settings had been lost or anything, everything looked fine, but after leaving BIO ist just right booted back into it, not into Windows.
My SSDs are correctly showing in the NVME-Devices, but not in the Boot-Tab

In the secutre Boot Tab the OS-type was set to other OS, and PK state was unloaded. When I change to Windows UEFI, it's loaded again, but same behaviour.

the CSM is disabled, when I enable it, the Drives show up in the Boot-Menu, but can't load into Windows.

System specs: 
AMD RYZEN 5950X
ASUS Crosshair Extreme
32Gb GSKill 3800CL14
9070XT Graphics
Samsung OEM 2TB Gen4 NVMe-SSD

 

Thing's I've tried so far:
Reset Bios,

switched to alternate Bios

Changed all the CSM-Secure Boot settings around

Unplugged all other devices from PC before booting,

removed half the RAM and all other SSDs from system

nothing changed.

 

All this seems to point to an issue with TPM/GPT/MBR-Partioning, but I am certain, the last Installation was already on an GPT-Partition, as I had to manually change it when moving to PCI-e4 Graphics Cards with Resizable Bar Support.
And I didn't change anything yesterday that could have caused this.

Might  Windows-Updates have borked this?
Any further ideas what to do?

Last resort is new Windows installation but I really would like to avoid this right now...

[GraysonJ90]

4 minutes ago, Ratisbona said:

Hello everyone,
I booted up my gaming-PC yesterday after work and it worked perfectly fine, like everyday for the last few years. I then left the room for a while, and when I came back it showed the BIOS Screen.
No settings had been lost or anything, everything looked fine, but after leaving BIO ist just right booted back into it, not into Windows.
My SSDs are correctly showing in the NVME-Devices, but not in the Boot-Tab

In the secutre Boot Tab the OS-type was set to other OS, and PK state was unloaded. When I change to Windows UEFI, it's loaded again, but same behaviour.

the CSM is disabled, when I enable it, the Drives show up in the Boot-Menu, but can't load into Windows.

System specs: 
AMD RYZEN 5950X
ASUS Crosshair Extreme
32Gb GSKill 3800CL14
9070XT Graphics
Samsung OEM 2TB Gen4 NVMe-SSD

 

Thing's I've tried so far:
Reset Bios,

switched to alternate Bios

Changed all the CSM-Secure Boot settings around

Unplugged all other devices from PC before booting,

removed half the RAM and all other SSDs from system

nothing changed.

 

All this seems to point to an issue with TPM/GPT/MBR-Partioning, but I am certain, the last Installation was already on an GPT-Partition, as I had to manually change it when moving to PCI-e4 Graphics Cards with Resizable Bar Support.
And I didn't change anything yesterday that could have caused this.

Might  Windows-Updates have borked this?
Any further ideas what to do?

Last resort is new Windows installation but I really would like to avoid this right now...

An amazingly likely possibility here is that it automatically updated windows and corrupted the update. Now windows is probably corrupted and destroyed the boot files, which is why its not being recognized as a boot device.

Reinstall windows might be the only choice.