Asus ROG Strix B450-F Gaming II black screen after power loss

Hi guys,

I have 7 AMD gpus (mix of RX 6800 and RX 6700XT) plugged into the Asus ROG Strix B450-F Gaming II and it works very well once booted. I have 4G Decoding, Gen1/Gen 2 active etc

If I reboot my rig, there is no problem, the rig will come back up and work.

If I shutdown via HiveOS or if the power cuts, the following behavior happens:

  1. I plug the power back
  2. The rig powers up but never shows the bios screen, the screen stays black and never gets to HiveOS.

Solution steps:
3) Unplug all PCIe risers from the motherboard except the one plugged into the main PCIe port and power up the rig.
4) As soon as the Bios Logo shows, press DEL then go and change a setting (seems like any settings works) then save and exit. At that point, power off the rig, plug the risers back and it will boot.

Note 1: I absolutely need to modify and save the bios. If I don’t do it, with only 1 gpu, the will boot and go to HiveOS but if I shutdown and plug the gpus back, I still have the problem.

Note 2: When there is a modification of the number of GPUs plugged, I noticed that the rig will boot the first time and automatically shutdown after 1 or 2 seconds, then reboots itself.

Do you know what is going on with this motherboard? Obviously all the cards and risers are working, it’s only when I edit and save the bios that the problem is solved (until next time!)

Thanks