Odd behavior on B550M Mortar Wifi

[aspara124802a3]

Bit of an odd issue and I'm not quite sure what to try next. I've built and repaired hundreds of PCs and it could be me having a blonde moment in my old age.
B550M Mortar Wifi with latest 1B BIOS installed.
AMD 3900XT and 4 x 16Gb Corsair ram with NZXT Kraken AIO.
2 x m 2 nvme drives and a HDD. Boot drive is built in legacy mode
Everything running at stock speeds, no overclock applied, not even xmp profiles at this point to debug.
When I turn the PC on, initially EZ-debug shows red CPU led and PC does not POST. Press reset button without powering down and PC will boot normally.
I've swapped known good ram, swapped known good GPU, repasted AIO, reflashed BIOS, checked all MB driver's even though that shouldn't be a factor pre-post, reset CMOS, but problem persists.
This didn't happen until after an update to 1A BIOS.
Next thing I'll try is an air cooler to eliminate the AIO not starting as the cause, but....
What have I missed?

 

[Alan J T]

Bit of an odd issue and I'm not quite sure what to try next. I've built and repaired hundreds of PCs and it could be me having a blonde moment in my old age.
B550M Mortar Wifi with latest 1B BIOS installed.
AMD 3900XT and 4 x 16Gb Corsair ram with NZXT Kraken AIO.
2 x m 2 nvme drives and a HDD. Boot drive is built in legacy mode
Everything running at stock speeds, no overclock applied, not even xmp profiles at this point to debug.
When I turn the PC on, initially EZ-debug shows red CPU led and PC does not POST. Press reset button without powering down and PC will boot normally.
I've swapped known good ram, swapped known good GPU, repasted AIO, reflashed BIOS, checked all MB driver's even though that shouldn't be a factor pre-post, reset CMOS, but problem persists.
This didn't happen until after an update to 1A BIOS.
Next thing I'll try is an air cooler to eliminate the AIO not starting as the cause, but....
What have I missed?

Roll back to BIOS 1.2.0.3 BIOS 7C94v18 and see how it goes

What GPU are you using as your build is Almost identical to what I was using last month till I upgraded from 3900X to the 5900X

MSI MAG B550M MORTAR WIFI To be Replaced with X570S Tomahawk Wifi
AMD Ryzen 9 5900X 12 Core Previous R9 3900X
Radeon RX 6800 Sapphire Pulse. Previous RX 5700 XT
G.Skill Ripjaws V 64GB F4-3200C16D-16GVK
M.2 PCIE 3x4 2500-MBps read and wright
2TB NVMe PCIe Game Drive 3300-MBps read and wright
Enermax D.F Series 850W PSU
CPU cooler Be Quiet Dark Rock TF
Windows 10 Pro

AMD Ryzen 9 5900X @ 4381.56 MHz - CPU-Z VALIDATOR

[kvpsk1] Validated Dump by ALAN-J-T (2022-04-30 15:00:45) - MB: MSI MAG B550M MORTAR WIFI (MS-7C94) - RAM: 65536 MB

valid.x86.fr

 

[aspara124802a3]

Running a 3060, but I've also swapped out with a 2060 Super just in case it was that. My gut is saying AIO. Vaguely remember in the mists of time late 90s a problem with a friend's pump not spinning up fast enough meaning it wasn't detected and mb protected the cpu. Not sure partner would be impressed if I swapped her 3900 into mine to test.

 

[Alan J T]

Have you turned of TPM as the newer BIOS enable it and not sure how well it works with BIOS in CSM mode. I only have used UEFI for the last 6 or 7 years.

 

[aspara124802a3]

Good call, but that hasn't made a difference. I'm on CSM because I'm too lazy to convert using mbr2gpt.

 

[aspara124802a3]

Ok, converted to UEFI to eliminate that. Still doing the same. Replace the AIO is my last guess, but I'll also roll back the bios just in case

 

[Alan J T]

Ok, converted to UEFI to eliminate that. Still doing the same. Replace the AIO is my last guess, but I'll also roll back the bios just in case

You could try setting the PUMP to 100% in the bios and see if problem continues or swap from PWM to DC in pump setting.

You can also turn off Smart Fan mode and just have it at 100% as well

 

[el_raberto]

I feel your pain.

PC working fine more or less since built in July 2020. I had updated to the 7C94v1B BIOS prior to wasting a long weekend trying, unsuccessfully, to upgrade to Windows 11. I was previously on the 7C94v13. Since 17/05/22 the PC boots for a second or 2 displaying the EZ Debug CPU LED, no USB mouse or keyboard etc detected at this point, then it powers off and the reboots as normal to desktop.

Over the last few days I’ve tried various things, some from my own past experience and some suggestions from other websites. I looked at my BIOS settings, pretty much knowing they’d have no impact on the issue but could do no harm – everything was all set as per previously working BIOS for past 1½ years

Cleared the CMOS – no difference.
Booted with XMP disabled – no difference.
I didn’t swap / remove / use single RAM stick as I had a previous RAM issue that I resolved a couple of months ago, so I was confident my RAM was good.
Disconnected USB 3.0 switch, used old PS2 keyboard and a mouse directly to PC – no difference.
Possible faulty Power button - swapped the Power & Reset button connections and powered on via Reset button – no difference.

At this point, I’d given up, I was thinking of just living with this weird 2 attempt power on issue and wait for the new BIOS update due but when you made your post, I thought I’d just try a BIOS flash back, using M-Flash. I was going to go back to my own last known good version, 7C94v13 but went for Alan J T's suggestion of 7C94v18 – perfect, now boots normally! I think your cooler my well be fine, just try the BIOS flash back.