Question New build, need help with CPU not detected or failed ez debug CPU light ?

Apr 23, 2022
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I just finished my new build ( second of all time) and the computer won't post with ez debug cpu light turned on.

Both motherboard 24 pin and cpu 8+4 pin are connected in both PSU and motherboard.

The motherbord ez debug cpu light is solid red and no output to display with HDMI cable connect to GPU.

All fans are spinning, and the case and mobo leds turn on. Also, rest of the debug lights turn on for a second, but only the cpu stays on.

Build is all new, except for the GPU:
  • CPU: Ryzen 9 5900x,
  • MOBO: MSI mag x570s tomahawk max wifi,
  • PSU: seasonic focus gx 850- gold,
  • RAM: G.Skill tridentZ NEO 3600mhz, cl 16.
  • NVME drive : WD SN850
  • GPU: inno3D RTX 2060
  • Cooler: Noctua nh-d15s
Booting the system with no RAM produces the same result, only the CPU light is on.

I tried reseating the ram, plugged it one at a time in any of the positions ( both of them, i got 2 sticks). The ram is working as i tried it on another pc i got and it booted.

Triple checked the PSU connections for ( both 24 pin for motherboard and 8+4 for CPU). Not sure if cables are working, but i swapped the cpu ones around and still nothing)

I also uninstalled the nvme drive ( wd sn 850 seated in first position). no success.

Removed the cooler, triple checked the CPU pins, nothing is bent and i see no damage or thermal paste in the motherboard socket.

I also reset CMOS by removing the battery for 1 hour while psu is unplugged and shorting jbat1 connectors multiple times.

Updated BIOS with flashback ( it took about 5 minutes while both usb led and mobo white led flashed, after which the system restarted) so presume this was a success.
Motherboard has "amd 5000 series desktop ready" printed on the box as it's a model launched late last year.

I have no other CPU or motherboard with which to test if CPU or motherboard is DOA.

The cpu heats up if i leave the system running even with the red cpu light on.

I also tried powering it up without the GPU, again, only CPU light turns on.

Only thing i did not do is reamove the MOBO from the case, but i unplugged every other component ( SSD and case connections).

Any other suggestion is appreciated as i am running out of ideas .
 
Last edited:
Apr 23, 2022
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Sup dude,

you could be potentially chasing our tail here as it is a known bug with the mobo where the CPU EZ debug light stays on even after a successful boot. (depending on bios version)

saw this comment in another post about similar issue with an X570 Tomahawk

"I had the same issue today, updated to 7C84v15 and not posting anymore (solid debug led on cpu) . Flashback with the same firmware, no posting, flashback to v13 (my previous bios) , everything works fine. Dont know whats the problem with v15."

so might be worth downgrading bios version for testing purposes

have you got a different GPU you can test with at all? maybe a cheap hd gpu that runs off PCI lane power without need for dedicated PSU supply?

apart from that buddy youve tried most of the troubleshooting tests i wouldve done, assuming they are new you could always RMA them
 
Apr 23, 2022
2
0
10
0
Sup dude,

you could be potentially chasing our tail here as it is a known bug with the mobo where the CPU EZ debug light stays on even after a successful boot. (depending on bios version)

saw this comment in another post about similar issue with an X570 Tomahawk

"I had the same issue today, updated to 7C84v15 and not posting anymore (solid debug led on cpu) . Flashback with the same firmware, no posting, flashback to v13 (my previous bios) , everything works fine. Dont know whats the problem with v15."

so might be worth downgrading bios version for testing purposes

have you got a different GPU you can test with at all? maybe a cheap hd gpu that runs off PCI lane power without need for dedicated PSU supply?

apart from that buddy youve tried most of the troubleshooting tests i wouldve done, assuming they are new you could always RMA them
Thanks a lot for your reply.

The motherboards in question are different, mine is x570s, a newer version. It came with BIOS 7D54 ver. 1.1 as written on the motherboard, and i updated it to ver 1.2 ( latest version on msi website). I am not sure if the update succeded, since i couldn't post either way, but the behavior of the flashback led makes me believe it was a success. I did not think to downgrade to ver. 1.0 since i saw some bugs reported on that one.

The gpu is working ( i used it on a different system, and retested it after the failed boot attempts).
 

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