[SOLVED] Unable to boot after changing CPU. ASUS B550-PLUS AC-HES

[barrette4197]

I recently (2 weeks) built a new NAS system with an ASUS B550-PLUS AC-HES motherboard and AMD Ryzen 5 5500 CPU. I later realized that the 5500 doesn't support ECC RAM, so I bought a Ryzen 5 5600T to replace it. System was successfully running TrueNAS, that I originally installed from a bootable USB drive. My boot drive is an NVME drive installed into the first M2 slot. I also have 4 SATA drives that are just used for storage.

Today I installed the new CPU, and on first boot I got this fTPM message
We detected a new fTPM firmware version/processor, which will change the data/structure of the storage space for firmware TPM.
If you did not apply fTPM function, please press Y to continue.
if you have Bitlocker or encryption enabled via fTPM, please follow instruction below:
Press Y to reset fTPM, please ensure to back up your recovery key, or the system will not boot without a recovery key

Press N to keep previous fTPM record and continue system boot, but fTPM function will not enable. You can swap back to the previous BIOS/processor to recover TPM related keys and data

I pressed Y and it rebooted, but I get a grub error, error: unknown filesystem. I fortunately hadn't actually used the NAS for anything yet, so I figured I would just do a clean re-install. I plugged in the same bootable USB drive I used previously and rebooted, this time going into BIOS. The USB drive is the only drive that shows up in the boot order. My other drives are all visible, but I can't add them as bootable. I saved and exited, but the system never boots from the USB. It gives the same grub error. I have also unplugged the NVME drive, same grub error. I have also reset the BIOS by shorting the CLRTC pins on the board, but it's always the same behavior.

 

[Lutfij]

Welcome to the forums, newcomer!

Are you able to get into BIOS without any issue? What BIOS version are you on for your motherboard? See if you can drop the older processor onto the socket, get into BIOS, then disable fTPM. Power down and then swap the processor to the 5600T and see if that prevents you from reinstalling the OS.

Thereafter see if re-enabling fTPM in BIOS brings you back to the OS without a reinstall.

 

[barrette4197]

My BIOS version is 3611 x64, build date 9/29/2024. I am able to get into the BIOS every boot by pressing DEL or F2.

I re-installed the previous CPU, and when I booted I got the fTPM screen again. This time I pressed N, and it took me into BIOS. The BIOS shows no bootable devices, but I can see all my drives, they just can't be added to the boot order. I went into Advanced -> AMD fTPM Configuration.

Selects TPM Device was set to "Enable Firmware TPM". I changed it to "Enable Discrete TPM"
Erase fTPM NV for factory reset was set to "Enabled". I set it to "Disabled"

I rebooted and still no bootable devices, so it went into BIOS settings. I plugged in the bootable USB and rebooted. This time, the USB shows as the only bootable device, but if I let it boot I get the grub error.

I went back in BIOS and changed:
Erase fTPM NV for factory reset to "Disabled"

It doesn't make any difference. I get the same grub error and can't add any boot devices other than the USB.

I installed the new CPU again, on first boot it notes that the CPU has changed (no fTPM notice this time) and asks me to enter BIOS to setup. In BIOS it's the same issue, no bootable devices.

EDIT:
I think I solved this by re-imaging the USB drive with DD mode instead of Iso-Hybrid mode. I don't know why this works, because it worked fine in Iso-Hybrid mode previously, but now it's booting off the USB drive.

 

[JayGau]

How did you create the TrueNas install boot drive? Did you use Rufus to flash the iso? Did you get the latest version? Is the boot setting set to UEFI in the BIOS?

I don't see why FTMP would prevent you to boot from non-encrypted drive, unless there is a problem with the TMP module. Check if secure boot is enabled in the BIOS. If it is, disable it and see if you can boot with the USB flash drive.

If that doesn't work, you could try to create a Ubuntu bootable drive (with Rufus) and see if you can boot from it. Ubuntu bootable drives are very easy to boot from so if you can't boot with that there is likely problem with the board (or the CPU).

 

[barrette4197]

Yes, I created the bootable drive with Rufus. The original drive was TrueNAS Scale 24.10.2.1, but since then 25.04.0 released, so that was the version that I just got to boot a short time ago. Both 24.10.2.1 and 25.04.0 I originally tried in Iso-Hybrid mode and that didn't work (although it did work with 24.10.2.1 initially when I first built the machine). I finally thought to try re-imaging in DD mode with 25.04.0 and that worked.

 

[JayGau]

Yes, I created the bootable drive with Rufus. The original drive was TrueNAS Scale 24.10.2.1, but since then 25.04.0 released, so that was the version that I just got to boot a short time ago. Both 24.10.2.1 and 25.04.0 I originally tried in Iso-Hybrid mode and that didn't work (although it did work with 24.10.2.1 initially when I first built the machine). I finally thought to try re-imaging in DD mode with 25.04.0 and that worked.

Oh sorry, I haven't seen your edit before posting my comment. I just tried to load the latest TrueNAS iso in Rufus and I got a pop-up window saying that this image is an iso-hybrid but its creator didn't make it compatible with this mode, so the DD mode will be enforced.

 

[barrette4197]

No worries. I marked the post as solution. Thank you (and Lutfij) for the help.