PC Processors

[mz01]

I am stuck in a BIOS loop (keeps going back to BIOS regardless of settings) and unable to boot after I upgraded from 3900x to 5950x without changing anything else in the system.  I have tried quite a few things detailed below, including removing all peripherals, re-seating everything, and re-flashing the BIOS.

Are there any recommendations to remedy this?  At this point I think I need to RMA the CPU.

Mobo: MSI x470 Gaming M7 AC

• Upgraded to E7B77AMS.1I1 (2022-07-19) with AGESA
• Prior to switching to the new CPU, had new BIOS for a week with no problems

RAM: 4x 16GB, Corsair (listed as supported)

GPU: Asus Tuf 3080 Ti

HDDs, SSDs, and NVME 2.0

PSU: Seasonic 1000 watts

Previous CPU, 3900x

New CPU, 5950x

Symptoms / Remedy attempts

• New CPU installed
• POST into BIOS, says BIOS was reset
• CPU temp reads 32 C
• Repeatedly goes into BIOS
• No changes, cycles immediately back into BIOS
• Changes, does reboot and back into BIOS
• Regardless of change... tried disabling Security Device Support, nothing works
• Eventually, after several reboots, motherboard will give a B4 error, which is listed as a DXE progress code for USB Hot Plug.
• I did disconnect all USB devices and motherboard USB connections, but gives input error
• Remedy is to reset CMOS and goes back to BIOS cycle

Latest BIOS details

Title AMI BIOS

Version7B77v1I1(Beta version)

Release Date 2022-07-15

File Size9.61 MB

• Description:
  - Update to AGESA ComboAm4v2PI 1.2.0.7. - Change the default setting of Secure Boot.

Previous BIOS attempt

Title AMI BIOS

Version7B77v1E

Release Date2020-06-16

File Size9.42 MB

• Description:
  - Update AMD ComboAm4PI 1.0.0.6 - Fixed HDMI audio lost issue when use AMD RX570 vga card.

0D code. ... could not roll back

[cpurpe91]

Is your boot device set to boot first?

Other than that I would assume there is nothing else to do but maybe try the CPU in another system but you probably would have if you had a compatible system.

Have you pulled out the CPU and reseated it yet? 

Have you tried the old CPU to see if maybe the board is damaged?

Have you tried disabling secure boot?

[mz01]

Fair questions

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@cpurpe91 wrote:

Is your boot device set to boot first?

Yes, set my boot device properly. I never make it into the boot selection screen, though. All the SSDs and HDDs do show up in the BIOS, so they are working fine.

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@cpurpe91 wrote:

Have you tried disabling secure boot?

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Disabled it in the BIOS, but it just brings back the BIOS screen (with the setting still disabled).

---

@cpurpe91 wrote:

Other than that I would assume there is nothing else to do but maybe try the CPU in another system but you probably would have if you had a compatible system.

Have you pulled out the CPU and reseated it yet? 

Have you tried the old CPU to see if maybe the board is damaged?

I have re-seated it, to no avail.

I have not yet put back the old CPU because I am out of thermal paste--I get more delivered tomorrow and will try that.  I imagine it will work, since nothing else changed, but it would be a good idea to eliminate the coincidence the mobo went out when I changed the CPU.

Another system to test would be very helpful, but I do not have one available to me.

[cpurpe91]

The last thing I would say is to try the old 3900X. Shot in the dark question but should I assume you have all of the CPU power cables plugged in? 

[mz01]

Just put back the 3900X and cleared CMOS. It went into BIOS, I did minimal settings changes, and it immediately booted.  The 5950x CPU must just be bad...

[mz01]

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@SohamMaoor wrote:

It looks like the bios didn't take and the board is trying to fix. If you can. Clear cmos then update bios again. When you do make sure your plugged into a good power source. power instability it can mess with the install. The board has usb flash make sure your in the correct usb slot. It will update through any usb slot with cpu but will only do it without a chip in one. If that doesn't work you may have to rma.

---

Good suggestions, I tried all of those.  With 5950x in there:

• Disconnected power cable
• Waited until mobo power light went off (took 15 seconds)
• Pressed / held the power button for 60 seconds to discharge anything left
• Removed CMOS battery, left it disconnected for 5 min
• Cleared CMOS (with jumper and clear CMOS button on rear of mobo)
• Reinstalled battery, powered on computer
• It went into BIOS, said CMOS cleared and Time in BIOS was reset to 2018

I still got stuck in the BIOS loop with the 5950x, and after a few restarts it fails to POST or go into BIOS and the mobo gives me the "B4" BIOS error code.  I need to go through above steps to reset CMOS to get back into the BIOS loop.

I re-installed the old CPU, the 3900x, and it immediately booted properly.  I didn't need to change anything else.  I think the 5950x is bad. I am going to RMA it.

[mz01]

I received the replacement CPU, popped it in, and I am receiving the same error, BIOS loop as before... At this point I am thinking this is the motherboard, but I am not really sure.  🤷‍

[cpurpe91]

Are you 100% sure that you are running the latest BIOS available? I read earlier in the thread you are running a version from 2020. That is why I am asking. 

[DimkaTsv]

@cpurpe91 He wrote that he attempted to rollback, but you cannot do it after updating to Zen 3 support ...

Hmmm... Does POST screen show you any specific error? Or just bootloops? 
It ... technically... may be some strange CPU to RAM incompatability especially as you use 4x16GB... 
Try to use 1-2 sticks to begin with? 
I just read there were some issues with cold boot for this mobo. Maybe they still remain? 
https://www.reddit.com/r/MSI_Gaming/comments/e5jct7/x470_gaming_m7_ac_cold_boot_potential_fix/
https://www.reddit.com/r/AMDHelp/comments/cd5qhn/3900x_msi_x470_gaming_m7_ac_bios_loads_but_os/

So... worth trying i guess? 

[mz01 · Accepted solution]

BIOS default is set on CSM mode when AMD 3000 series CPU is installed, for AMD 5000 series default BIOS mode is UEFI.

The solution for my circumstance was to change the BIOS boot type from UEFI back to CSM.

To enable CMS (over UEFI) go to BIOS -> Advanced -> Windows OS Configuration -> Select BIOS CSM/UEFI Mode as "CSM"

This problem was specific to my Unraid OS (Linux) installation, since my Ubuntu Live USB worked with both UEFI and CSM. So, Your Mileage May Vary.
This also fixed my Debug Code LED reading 'b4' upon restart (it restarts normally now).

Why the BIOS boot type default changed between 3000 series and 5000 series (running the same BIOS version) is beyond me, but that is what caused my problem.

THank you for all the help! I used MSI's forums to help me solve this one. https://forum-en.msi.com/index.php?threads/solved-x470-bios-loop-after-cpu-upgrade-from-3900x-to-595...

Edit: that also means there was no need to RMA the first CPU, so sorry about the extra overhead, but thank you for the fast service on that.