Question Asus Prime B550 Plus - works with 3900x but not 5800x on the latest bios

[dbs8888]

I have bought a Asus Prime B550 Plus as an upgrade to my Asrock B450m HDV R4.0. Everything was working on the Asrock B450.

I transferred my 5800x, 3080ti and 2x16gb ram and it would not post :-( I thought it may be the bios so switched out the CPU for a 3900x and it booted fine this time and I updated the bios to the latest version 3002. I reboot and it showed the updated bios version.

I switch the CPU back to the 5800x and it would not post it powers up, you can hear it adjusting the CPU fan rpm, but it just cycles through the ram, CPU and GPU QLED leds endlessly.

I've reset the bios multiple times, tried different ram with 1 and 2 sticks, I switch out the GPU for a Nvidia 710. Not change.

The support is not much help either just asking me to use QVL ram.

Any ideas what it could be?

 

[dbs8888]

I've also tried 2 other bios versions, older cpu for bent pins and checked the socket for debris too nothing.

I reseated the CPU and GPU and ram a number times as well as the power sockets.

I hoping someone can figure it out or has solved something similar.

 

[logainofhades]

If everything is working with the 5800x, other than the B550 board, it leads me to believe it is a faulty board.

 

[dbs8888]

I'm confused though as the same board works with the 3900x