Question B550-A-Pro Boot issue (White CPU debug LED)

Feb 28, 2024
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Having recently upgraded my PC, which I am generally happy with I have suddenly encountered some issues that I am going to outline - any input is appreciated:

Specs:
MSI B550-A-Pro,
Ryzen 7 5800x3D,
AMD 6750XT 12GB,
Kingston 64GB DDR4 3600Mhz
1Tb WD Black Gen4 M.2
500GB WD Blue Gen3 M.2
Other misc drives, fans, RGB's
(Older) Corsair TX750M

The PC was working well, I had been using it for about a week but to avoid stuttering I turned off ULPS, plugged a separate PSU PCI cable into my graphics card in oppose to the splitter. I also installed an RGB strip.
The PC would then turn on in terms of lights, fans, the motherboard LED's - but not boot, showing a white CPU debug LED. I could not even get to bios (which is the most recent version).
There was no output to my monitors or keyboards.

I tinkered after reading reddit posts, reinstalling things, resetting CMOS the only thing I did not do is re-seat my CPU.

MAKE DO SOLOUTION: The solution I actually find to actually I found to boot and get into windows was swapping the M.2 drives,
So; the 500gb Gen3 Storage M.2 is now in the first slot and the 1tb (OS boot) Gen4 drive is in the gen3 second slot.

My PC now works, but I am not getting all the performance of my main M.2 (the 1tb OS drive) as it is in the Gen3 as it will not boot when in the Gen4 slot.
See table which should explain when the issue occurs:

Slot 1 Gen4Slot 2 Gen4Does the PC get past the white CPU debug LED?
1tb OS Gen4 M.2 WD Black500gb OS Gen3 M.2 WD BlueWhite CPU debug LED, with or without heatsink.
500gb OS Gen3 M.2 WD Blue1tb OS Gen4 M.2 WD BlackWorks as normal but inefficiently
500gb OS Gen3 M.2 WD BluePosts to BIOS, no OS drive.
1tb OS Gen4 M.2 WD BlackPosts to windows, no storage drive.
1tb OS Gen4 M.2 WD BlackWhite CPU debug LED, with or without heatsink.
I haven't yet tested if the 500gb Gen3 posts to bios in the slot1 on its own.

QUESTION: Has anyone encountered issues like this? Will I need to return my motherboard?
 
Feb 28, 2024
4
0
10
bios up to date and the firmware of the m.2 as well?
I updated the bios - not working when they are in the slots, however I have narrowed it down further

When the Gen4 SN850x m.2 is in the first slot, but not screwed in (hanging out) the computer will boot.
When it is screwed in it will not boot.

There are no issues when the m.2 is in the second slot, or when the gen3 m.2 is in the first slot.
 
are you using the correct screw and standoff?
maybe the screw is too long or too wide?

this would be wrong:
https://www.reddit.com/media?url=https://preview.redd.it/is-the-m-2-ssd-supposed-to-bend-like-that-v0-0lw27ufj70s81.jpg?width=1080&crop=smart&auto=webp&s=6e8a22b051f1942fbe8a36b24200aa27931561cb

did you mount the standoffs correctly and none is underneath the m.2?

are you using the M.2 cooler from the motherboard?
did you place it on the M.2 correctly?
Does the wd black have a heat sink itself? then you will need to remove the thermal pad from the heat sink of the motherboard or you just don´t install the heat sink of the motherboard
View: https://www.youtube.com/watch?v=eR1JY2M74wE
 
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