Help: MSI MAG X870 Tomahawk WiFi stuck in continuous POST loop (Codes 16, 0A, 8A, 85, F3, 4F, 88)

M

mdubose157702d5

New member
Joined
Jul 13, 2026
Messages
4
Hey everyone, I’m dealing with a frustrating POST issue on my desktop rig and could really use some expert advice.
My Specs:
Motherboard: MSI MAG X870 Tomahawk WiFi (with EZ DIGI-DEBUG LED)
GPU: AMD Radeon RX 9070 XT
OS: Windows
The Problem:
My system is stuck in an endless boot loop and absolutely will not POST. I have no display output and I am completely locked out of the BIOS.
The Symptoms:
The motherboard debug LED never reaches the OS handoff or the CPU temperature display. Instead, it constantly cycles through this exact sequence of codes over and over: 16 -> 0A -> 8A -> 85 -> F3 -> 4F -> 88.
From what I've researched, 16 is pre-memory initialization, 4F is DXE IPL, and F3 means it's looking for a recovery firmware image, but I can't get the system to snap out of this loop.
What I’ve Already Tried:
I completely removed and reseated both sticks of RAM, but it didn't change the behavior at all. The loop continues exactly as before.
Has anyone successfully recovered from this exact sequence? Should my next step be trying to force a blind BIOS update using the physical Flash BIOS button on the rear I/O, or does this look like a hardware failure with the motherboard or the CPU's memory controller?
Any help or guidance is incredibly appreciated!
 
Sort by date Sort by votes
Do any of the EZ Debug LEDS light up when being stuck? Could you try booting from the iGPU of the CPU and see if that gets you into the BIOS? Can you tell us what CPU you are using?
 
Upvote 0 Downvote
"Thanks for the reply!
Regarding the EZ Debug LEDs, it is cycling through the codes I mentioned (16, 0A, 8A, 85, F3, 4F, 88) and never settles on just one light or displays the CPU temperature.
I haven't tried booting from the iGPU yet, but I will give that a shot right now.
My CPU is a Ryzen 7 7800X3D.
I'll report back once I've tested the iGPU!"
 
Upvote 0 Downvote
"Hey again, I just tried removing my dedicated GPU and booting directly from the motherboard's iGPU.
Unfortunately, the behavior changed, but it's still not posting. Now, the debug display is completely stuck on code 00, and the top red CPU EZ Debug LED is solidly lit. It just sits there forever and I still can't access the BIOS.
Since code 00 with a solid red light usually means it's completely failing to communicate with the processor, do you think the BIOS is completely corrupted at this point? Should my next step be forcing a manual BIOS Flashback using the USB port on the back, or does this start to look like a hardware failure with the motherboard itself?"
 
Upvote 0 Downvote
Is this a brand new build? If so, it is unlikely the BIOS is corrupted.
Check your CPU first for any bent pins
List all of your hardware specs for better troubleshooting, including complete description of the power supply.
 
Upvote 0 Downvote
"Thanks for the help! To answer your questions:
It is technically a build from last year, but I just replaced the motherboard and the power supply, so those two parts are brand new.
I already pulled the CPU out and checked for bent pins, and everything looks perfectly fine there. I actually managed to get it to boot into Windows earlier today using just one stick of RAM in the DIMMA2 slot. However, it still loops if I try to use both sticks, and it actually just did a sudden hard shutdown on me while idling in Windows (the PC completely shut off, but the RAM RGB stayed glowing).
Here is my complete hardware list:
CPU: AMD Ryzen 7 7800X3D
Motherboard: MSI MAG X870 Tomahawk WiFi
GPU: AMD Radeon RX 9070 XT
RAM: Corsair Vengeance RGB DDR5 (currently only running one stick)
PSU: MSI MAG A850GL PCIE5 850W 80+ Gold
 
Upvote 0 Downvote
mdubose157702d5 said:
I already pulled the CPU out and checked for bent pins, and everything looks perfectly fine there. I actually managed to get it to boot into Windows earlier today using just one stick of RAM in the DIMMA2 slot. However, it still loops if I try to use both sticks, and it actually just did a sudden hard shutdown on me while idling in Windows
Click to expand...
Oh interesting, I was going to suggest testing it with 1 stick of ram and trying each ram slot individually to see if the behavior persists or not. Might be a dead memory channel, issues in the CPU memory controller, or maybe the motherboard itself if it's flaky and you can't reliably reproduce it. Have you tried flashing the latest BIOS just in case?
Also make sure the MB isn't making any contact with the case or any screw grommets that aren't the ones used to mount it ( could be shorting somewhere )

"it actually just did a sudden hard shutdown on me while idling in Windows"
I assume this was while only using 1 stick?
To remove extra variables, are you able to use your old PSU while debugging? I don't think the PSU is the issue since it's new... but when tracing down issues the fewer variables the better
 
Upvote 0 Downvote
Yeah, you need to be 100% certain that there are no bent pins, it has to be checked meticulously. Upload some photos to an image hoster (because of file size) and link them here, sometimes bent pins are so difficult to spot that I even missed one or two in the past, and I've looked at a lot of such photos. So you always want as many pairs of eyes inspecting it as possible. Reason being, should there be bent pins, you don't have to troubleshoot anything else, they will be 100% responsible.

About the Debug code display, usually that is less helpful than the four simple EZ Debug LEDs. You can look up the various debug codes in the manual, but in the end, they don't result in too much useful information. It's enough to know which EZ Debug LED(s) it's getting stuck on.

Using the Flash BIOS Button is something to try, sure. There's a procedure that has to be followed, and then it should flash for 5-8 minutes. But first there should be absolute certainty about not having any bent pins, which can easily happen on accident during CPU installation (open-heart surgery moment of any PC build).
 
Upvote 0 Downvote
Back
Top