Maybe this will work:
Ensure the monitor is connected to the primary GPU ( the one in the 16x slot closest to the CPU )
Disconnect the USB or SSD/HHD from the rig.
Fully power off everything: including the PSU.
Press the power button several times to clear any remaining power in the mobo.
Turn the PSU powerswitch back to | "on".
power on (without the USB attached)
See if the bios posts; if you get nothing in 20 seconds; press ctrl + alt + del repeatedly until the system reboots.
Wait and see if the bios posts.
If the bios posts attach the USB key to a USB 2.0 port and press ctrl + alt + delete.
if it boots; stop the mining process before it starts mining:
then go to the top left and click the ubuntu button
type u
and click on software updater
run updates
reboot
Let me know if this works.
I tried with a new motherboard MSI Z270 Gaming Plus with only one GPU directly connected to it, and a new PSU.
Same Result.
I have extra pendrives but I am not able to copy the image there because they are 15.5 Gb and I it needs 15.6.
If the bios posts; you can access the grub loader menu by pressing
esc
continuously while booting (note holding it down doesn't usually work), then select boot in recovery mode.
in recovery mode:
Enable networking
then install updates from the cmd prompt:
sudo apt-get update && sudo apt-get dist-upgrade --yes
and reboot
this should ensure your build has all known system files for your system.
I think I've found the problem, it is not solved by updating:
I installed xubuntu in a new pendrive. And did a apt dist-upgrade, after that, I rebooted and installed lastest amdgpu-pro drivers, and then it happended exactly the same.
I am able to press ctrl+f1 and work via command prompt, but it is not solved by updating.
I am still trying to connect the pendrive to the 2.0 USB port, but it is not recognized. Why do you suggest to do it like this?
Thanks for your help!