Dual monitor setup - One monitor goes to sleep, the other doesn't

Question

I never had this issue before but then I got a new video card and two new monitors. The monitors are identical but one is connected via hdmi and the other via display port. The hdmi monitor goes to sleep and the display port one doesn't, it just keeps displaying the Ubuntu screen for logging in. This causes windows from one monitor to move to the other if I log in before turning the other one back on.

How can I prevent this from happening?

Aside from this, even when neither monitor goes to sleep, sometimes the login prompt would be on the other monitor and that once again leads to them getting swapped in order.

Edit: requested info:

lspci| grep -i "video \| display \| vga"
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Polaris12 (rev c7)

and:

lshw -class video
WARNING: you should run this program as super-user.
  *-display                 
       description: VGA compatible controller
       product: Polaris12
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci@0000:01:00.0
       version: c7
       width: 64 bits
       clock: 33MHz
       capabilities: vga_controller bus_master cap_list rom
       configuration: driver=amdgpu latency=0
       resources: irq:48 memory:c0000000-cfffffff memory:d0000000-d01fffff ioport:e000(size=256) memory:fea00000-fea3ffff memory:c0000-dffff

The video card model is Gigabyte Radeon RX 550 D5 2GB Graphic Cards GV-RX550D5-2GD

Edit: I think the issue was a bad video card. Issue went away with a different radeon card.

Answer 1

First Try Updating Your Drivers Via PPA

Add the oibaf ppa for latest AMD drivers:

sudo add-apt-repository ppa:oibaf/graphics-drivers

and install any updates it makes available:

sudo apt update && sudo apt upgrade && sudo apt dist-upgrade

Reboot and try out the new drivers. If it works, your done! If not, try installing the pro drivers.

Download and Install Pro Drivers

If the above doesn't work. you can try installing amdgpu-pro. There is a complete guide at the AMD website. Here is a quick and dirty version:

Get the driver from here. Under linux tab, download the 18.04 version.

cd ~/Downloads
tar -Jxvf amdgpu-pro-*.tar.xz

Install the package:

cd amdgpu-pro-VERSION (whatever the name of your unzipped directory is)
./amdgpu-pro-install

You will need to enter your sudo password and provide some confirmations. Reboot and see how it works.

Sometimes Hardware Dies

Just because the above doesn't work for you, doesn't guarantee that your hardware is fried. HOWEVER... OP fixed issue with new hadware:

I think in the end the issue was a bad video card. The machine kept freezing on the screensaver every so often so I got a different video card, also radeon and both issues went away.

Unfortunately the fix isn't always free.