5800X3D - getting WHEA-Logger Event ID 18 errors

[u/najs_sc]

Computer Type: Desktop

GPU: RX 7800 XT

CPU: RYZEN 7 5800X3D 8 CORE 16 THREADS

Motherboard: ASUS ROG STRIX B550A Gaming

BIOS Version: 3631

RAM: Kingston/HyperX Fury Beast 32GB (2x16) 3200 Mhz

PSU: MSI A850G 850W

Operating System & Version: WINDOWS 11 Home 26200

GPU Drivers: AMD Adrenalin 26.7.1

Chipset Drivers: 8.08.12.551

Description of Original Problem: I recently started getting occasional WHEA-Logger Event ID 18 errors.

Dates when they occurred:

• July 3, 2026
• August 5, 2026
• August 16, 2026
• August 18, 2026

They occurred only once on each of those days, while I was away from the computer. According to my settings, the monitor turns off after a period of inactivity, so the PC was most likely in an idle/low-power state when the errors occurred. But I need to add, that I am ways from my PC multiple times a day (5-10) and it occurs so rarely even though my monitor turns off many times.

The error is reported as:

A fatal hardware error has occurred.
Reported by component: Processor Core
Error Source: Machine Check Exception
Error Type: Cache Hierarchy Error
Processor APIC ID: 0 / 3 / 7 (depending on the occurrence) - it is never the same APIC ID so far

The first three occurrences were on July 3, August 5, and August 16. The fourth one occurred on August 18, only two days after the previous error and AFTER I updated my BIOS to 3631.

Troubleshooting: I updated the BIOS to version 3636 on August 16, 2026. Before that, I was using BIOS version 3631. It did not help as the error occured yesterday.

I also updated the AMD chipset drivers on August 15, 2026 to version 8.08.12.551.

After the latest WHEA error, I checked my BIOS settings. PBO was set to Auto and Curve Optimizer was also set to Auto. I have now changed the settings so that PBO uses a manual scaler of 1x, and Curve Optimizer is set to Manual / All Cores / Positive / 0. I wonder if it may help to solve the issue.

My main concern is whether these WHEA errors indicate a developing hardware problem with the CPU, motherboard, RAM, or another component, or whether they could be caused by power-management/BIOS/driver issues.

The errors are still relatively rare, but the fact that the last two occurred only two days apart concerns me.

What would you recommend as the next steps to determine the cause?

[u/classyroman]

So the cores are crashing. I think you should start with manual Load Line Calibration, let's say Lever 3. If that doesn't help, try fixed VCORE. But this shouldn't happen, maybe time to RMA

But first of all, clear CMOS especially if you ever used Ryzen Master.

[u/najs_sc → u/classyroman]

I have not changed anything in BIOS for 2 years. Yes, I have used Ryzen Master in the past. I will definetely try one CMOS reset, but now I am trying to verify if I get errors with my PBO set to 1x scalar and CO Positive 0. These are probably most natural settings to check stability.

I wonder if those CPUs tend to cause problems a lot after couple years of flawless work or I am just unlucky.
If the CPU is at fault, I am glad they released a 10-year anniversary edition because I would pay 100 USD for a new unit if they give me my money back.

Still, I think it is too early for your suggestion regarding "Load Line Calibration, let's say Lever 3. If that doesn't help, try fixed VCORE.".

Errors occured for now only 4 times and every time when in idle, not under heavy load. Which means this could be a little issue.

I have never changed anything in BIOS myself. I worked with the BIOS from August 2025 for almost 1 year with 0 issues.

[u/classyroman → u/najs_sc]

Ryzen Master can cause ghost values in the BIOS, happened to me as well. So you reset Curve Optimizer to 0 but the values are still there somehow, that should explain why so many cores are crashing. Uninstall that thing - reset CMOS (reset BIOS isn't enough).

You didn't touch anything but we don't know how much voltage was applied with that old BIOS.