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Troubleshooting: build fails to boot after CPU change (self.buildapc)

submitted 8 months ago* (last edited 8 months ago) by rombert to c/buildapc

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I have a small headless PC that's been running as a server for some time. Specs below

Component	Details	Details
Motherboard	AsRock B450 Gaming-ITX/ac	https://www.asrock.com/mb/amd/fatal1ty%20b450%20gaming-itxac/index.asp
RAM	2 x Samsung M391A2K43BB1-CTD	https://semiconductor.samsung.com/dram/module/ecc-udimm-ecc-sodimm/m391a2k43bb1-ctd/
GPU	MSI GeForce GT 730 2 GB	https://www.msi.com/Graphics-Card/N730-2GD3V2/Specification
Case	Fractal Node 304	https://www.fractal-design.com/products/cases/node/node-304/white/
Boot SSD	Kingston A2000 250 GB, M.2 2280	https://www.kingston.com/datasheets/A2000M_prelim_us.pdf
PSU	Seasonic Focus GX 550 W	https://seasonic.com/focus-gx

I purchased a Ryzen 5 4560G CPU, as they have an integrated GPU and work with ECC RAM, so that I can free up my GPU for other tasks.

Unfortunately, after replacing the CPU the build fails to boot:

all fans spin up
no video signal (tried both iGPU and dGPU )
restarts after 20-30 seconds

I did two attempts to install the CPU, after the first one I realised that I forgot to upgrade the BIOS to at least version 4.40 ( https://www.asrock.com/mb/amd/fatal1ty%20b450%20gaming-itxac/index.asp#CPU ) , I was running 3.X . I reinstalled the old CPU, upgraded the BIOS to version 4.60 and installed the new CPU again. This failed again.

I am now runing with the old CPU, but I am out of ideas about what to try, assuming the new CPU is working as expected.

Does anyone have any suggestions I can try? I did not try to randomly reseat things as the build is pretty cramped.

Thanks!

Update: I managed to get this to work successfully. I reset the BIOS to defaults (did not short pin, just used the UEFI interface ) and reseated the RAM again (although I am not sure that did anything, never had problems with the RAM ).

One interesting tidbit is that the first time I booted I was greeted by a POST message along the lines of

New CPU installed, fTPT/PSP NV corrupted or fTPT/PSP BV structure changed

Press Y to reset fTPM, if you have BitLocker or encryption enabled, the system will not boot without a recovery key

Press N to keep previous fTPM record and continue system boot, fTPM will NOT enable in new CPY, you can swap back to the old CPY to recover TPM related Keys and data.

I pressed Y and I was able to boot with the new CPU. Something that is still not working is switching the boot GPU to the integrated one, but I'll keep digging. Thanks for all the help!

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[–] neatchee 5 points 8 months ago* (last edited 8 months ago) (1 children)

Odd as it sounds, I would try clearing CMOS completely or otherwise resting uefi/bios to defaults

After that my next step would be to disconnect literally everything (storage, peripherals, all non-cpu fans) except the CPU and a single stick of RAM. If that fails, try the other stick. Also try different slots for the single stick of ram

If it still fails to reach uefi/bios then pull the remaining stick of ram and see if it will even do a basic post

The goal here is to determine the minimum configuration in which it behaves as expected. There is expected behavior in all of these configurations (even without ram it should act in a specific way). Then start adding things back one at a time until you figure out what introduces the issue

All of that being said, if I had to bet I'd say it's just a faulty CPU.

[–] rombert 2 points 8 months ago (1 children)

Thanks for your suggestions. I managed to get this working after resetting UEFI to defaults and reseating the RAM. See my post update for details.

[–] neatchee 2 points 8 months ago

Hooray! Glad to have helped!! Enjoy your updated rig! :)

[–] Contramuffin 3 points 8 months ago (1 children)

Sounds like there's incompatibility of some kind. My first thought is to check to see if your CPU is compatible with the RAM. Maybe XMP is on and the CPU can't handle that RAM speed? Just a shot in the dark here

Alternatively, I've also had that happen if things aren't seated properly. It sounds like you've already tried that, though. So if it's not incompatibility, then I think the next most likely is that the CPU is defective

[–] rombert 1 points 8 months ago

Thanks for your suggestions. I managed to get this working after resetting UEFI to defaults and reseating the RAM. See my post update for details.

[–] cory_lowry 2 points 8 months ago

Kind of sounds like the new CPU might be bad.

[–] satanmat 1 points 8 months ago (1 children)

Oof. I think the first thing I’d check is the new cpu.

Or. Pull the gpu (booting the new CPU) to verify there is no compatibility issue?

[–] rombert 2 points 8 months ago

I tried to boot without the new GPU as I had to remove it to properly install the CPU cooler (stock AMD, I found it a pain). That did not help.

I already opened a warranty case regarding the CPU, I wanted to check if I was missing something.