Black screen on boot/installation Zorin OS 15.1

what is output of

lspci -vnn | grep '\''[030[02]\]'
cat /sys/kernel/debug/vgaswitcheroo/switch

I don't know if there's any point in that.

I want to see what drivers are loaded at start of X

Here you go:

And the output is

01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Redwood XT [Radeon HD 5670/5690/5730] [1002:68d8] (prog-if 00 [VGA controller])

For

cat /sys/kernel/debug/vgaswitcheroo/switch

I've got 'permission denied'.

BTW, I don't know if it's important, since I made this thread I switched from Zorin to Ubuntu 18.04. The boot problem still remains.

There's something odd about that log. Usually when the keyboard and mouse have been configured, that's it until X shuts down. But this log continues with another set of video messages. It looks almost as if the graphics card has been reinitialised. Now why would that happen, I wonder?

I looked again and there are two monitor outputs.

[ 52127.221] (II) RADEON(0): EDID for output DVI-0
[ 52127.221] (II) RADEON(0): Manufacturer: SAM  Model: 27f  Serial#: 1296380466
..............
[ 52127.222] (II) RADEON(0): Monitor name: SyncMaster
[ 52127.222] (II) RADEON(0): Serial No: HVJPC05521
......

and then at the end:

[ 52201.893] (II) RADEON(0): EDID vendor "SAM", prod id 639
[ 52201.893] (II) RADEON(0): Using EDID range info for horizontal sync
[ 52201.893] (II) RADEON(0): Using EDID range info for vertical refresh

Which is the one that isn't giving a signal?

I don't think this will show anything, but just in case, the output of

sudo cat /sys/kernel/debug/vgaswitcheroo/switch

Which is the one that isn't giving a signal?

There is only one. SyncMaster.

sudo cat /sys/kernel/debug/vgaswitcheroo/switch

cat: /sys/kernel/debug/vgaswitcheroo/switch: No such file or directory

When you get a black screen press alt-ctrl-f1, do you get a console login screen?

Originally Posted by colorpurple21859 When you get a black screen press alt-ctrl-f1, do you get a console login screen?

No. The keyboard is dead as well.

open a terminal post the output of

xrandr

when you get a black screen does ctrl-alt-f1 ctrl-atl-delete reboot the computer, may take 20-30 seconds to reboot.

Originally Posted by colorpurple21859 open a terminal post the output of xrandr

Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 8192 x 8192
XWAYLAND0 connected 1680x1050+0+0 (normal left inverted right x axis y axis) 470mm x 300mm
   1680x1050     59.85*+

when you get a black screen does ctrl-alt-f1 ctrl-atl-delete reboot the computer, may take 20-30 seconds to reboot.

No, it doesn't.

I'm not sure it would be of any help to anybody but I'll post it here anyway. It seems that the problem had nothing to do with software. One day i just put the graphic card in another slot on motherboard and it solved this thing. Anyway, thanks guys for your time.

Thanks for the update