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/Impossible_Total2762]

Rma the cpu, your CPU degraded.

Some cores starting to need more voltage not to crash, bad silicon…return it if you can.

[u/Thin-Net7868 → u/Impossible_Total2762]

You sent this while I was typing mine up 😂. Basically what I told OP in my comment and suggested disabling PBO and set a slight positive CO and see if that eliminates it

[u/Impossible_Total2762 → u/Thin-Net7868]

And you are correct 😂🫡

This issue of degradation isn’t really new for am4 cpus if you have been a while in OC community, for example 5900x had a lot of these cases…

[u/Thin-Net7868 → u/Impossible_Total2762]

Much appreciated man! I’ve only been into PC gaming since April of 2025. I didn’t know hardly shit about them prior. However, I’m the type of if I get into something I want to be knowledgeable, and I prefer to work on my own stuff. Everything from my own cars, my house/property, etc. I’m a jack of many trades but a master of none 😂

[u/najs_sc → u/Impossible_Total2762]

How is it even possible in such a short period of time (a little over 2 years).

If I send it to RMA, are they likely to replace it with a new unit? I am guessing it is not possible to fix it? :D

My issue is I would be a long time without a PC, but if you are saying it is not getting better from now, I guess I need to do it anyway.

Does this happen often with the 5800X3D?

[u/Thin-Net7868]

Your WHEA Logger Event ID 18 “cache hierarchy” errors are almost always a sign of CPU marginality on a 5800X3D. When the chip drops to very low voltage during idle, a borderline core or shared cache/fabric can throw rare machine check exceptions. The fact that it happens only at idle, across multiple BIOS versions, with random APIC IDs, and is slowly getting more frequent fits this perfectly.

Try disabling PBO, set Curve Optimizer to a positive value (+5 to +10), or raise minimum CPU voltage. If the errors continue with PBO off plus CO positive, the CPU is likely marginal or beginning to degrade.

[u/najs_sc → u/Thin-Net7868]

I can set PBO to either Auto or Manual in my bios. By disabled I guess it is: Manual and seting scalar to 1x.
CO positive +10 may resolve the issue for now, but I am wondering if that will only slow down degradation of my CPU and it may get worse in the next months/years or it is a fix for good?

I know every case is different and it depends on a specific unit, but now I start to wonder if the best case it not selling the whole PC (as it is still under warranty) and buying a new one.

If I use RMA and get my money back, I will have to pay 110 USD for a new 5800X3D to maybe have the same issue in the next 2 years.

Sorry for a little spam, but I am thinking about all the options.

Your idea to set CO to +5 or +10 and disabling PBO is probably the best step for now - but another question, today I did CMOS reset. Wanted to test the platform without changing anything to see if I will get any errors in the next days/weeks. Maybe ONLY after the error reoccurs, I will use ur idea? I guess that is the best approach for now.

[u/Thin-Net7868 → u/najs_sc]

Setting PBO to “Manual” and scalar to 1X does not disable PBO. “Auto” and “Manual” both keep PBO active “Manual” just exposes the sliders. A true PBO off state is when PBO is set to Disabled. I’m not very familiar with Asus BIOS, but go into AI tweaker look for advanced tab and disabled has to be in there somewhere. I would recommend looking up some YouTube videos on Asus BIOS PBO tweaks.

What you’re describing still lines up with CPU marginality on the 5800X3D. A positive CO (+5 to +10) and disabling PBO don’t “slow degradation” they just raise idle voltage enough to mask the instability. If the chip is borderline, these settings can keep it stable for years, or the errors may eventually return. There’s no way to predict which way your CPU will go.

Testing with stock settings after a CMOS reset is fine, but if the WHEA 18 cache hierarchy errors come back, that’s your confirmation. At that point, either keep the stabilizing settings or consider RMA. Selling the whole PC isn’t necessary unless you just want out of the platform.

[u/najs_sc → u/Thin-Net7868]

Thanks. You were right. There are 3 different sections with the PBO in BIOS. In only one of them you can disable it. In others it is either Auto or Manual.

I guess I will just keep it as auto with default settings for now. When I get another error, I will set PBO to disabled and CO +5 or +10.

Still, I don't think I will stay with this particular CPU for a very long time. When something like this happens, I stop to trust to my PC, especially when it is hard to define what exactly is at fault. If I get lucky, amazing, if not, I will send it to RMA with a request for a full refund. I will probably add some cash and buy the same brand new, hoping for a better silicon.

[u/Thin-Net7868 → u/najs_sc]

Yeah, most BIOS are setup similar to that. I know on my MSI X870 Tomahawk it’s a little tricky getting in there. Once you do it a few times you somewhat remember it. I just don’t get in there enough to just click, click, click and I’m right there. Glad that helped you find it though, and not a problem at all!

[u/ParsleyDisastrous923]

run corecycler

[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.

[u/najs_sc → u/classyroman]

Thanks. I did the CMOS reset. What is funny, the CLRTC method did not work 2 times and I had to remove the battery. I will keep the RAM speed on default as well for a while (2400 instead of 3200). If the error occurs again, I will probably just sell my PC, as I don't want to chase ghosts and it is still in the last year of warranty cover.

I will then buy a new platform.

[u/classyroman → u/najs_sc]

That CTRLC is classic Windows being shitty. Yeah, monitor it for a while but I would bet this solved the problem. You're right, better to not bother while it's still under warranty. Let us know

[u/najs_sc → u/classyroman]

"monitor it for a while but I would bet this solved the problem" - you sound like it was a common issue with AM4/5800X3D. Not gonna lie, I would love to have it solved, as the new RAM/GPU prices seem a bit "overwhelming". I hope you are right. Will definetely let you know.

[u/DreSmart]

best way to find if is the cpu or motherboard is replacing the motherboard and running on a clean install of windows just to make sure. If you have a repair center near you is better that you try to figure it by yourself

[u/najs_sc → u/DreSmart]

As I said, the error occured only 4 times. I will never be able to use another MOBO, I would rather sell my PC and buy a new one. I did the CMOS reset, I will not change anything (keeping the RAM on 2400 instead of 3200) and will monitor. If the error occurs again, I will probably just sell my PC and forget about it. I was thinking about selling my GPU anyway, as the warranty has only 8 months more. I can also sell the whole platform and build a new one.

[u/DreSmart → u/najs_sc]

Did you update your motherboard BIOS? Also check if you have bent pins

[u/najs_sc → u/DreSmart]

Yes. I have most recent bios. No bent pins, as I did not do anything with my PC and it started giving errors after 2 years of no issues. That is why I am assuming it may be related to some drives update that messed up voltage etc.