SOLVED AMD onboard graphics, DVI connector gives bad video

[linuxgrrl]

Hello ,
fresh install of 20.1 Cinnamon on a machine with AMD Ryzen PRO 4350g CPU/graphics. I installed the "Edge" version of mint as directed. Full specs are below. I get perfect video through the HDMI output. However, now I need to give my spouse back her hdmi monitor and use my own. Mine has a (I think it is called) DVI connector and the video is horrible. Everything is red like lava, and the video is just barely is visible enough for me to shut the computer down with the mouse. It also won't play the x startup sound correctly -- it plays half of the sound and then repeats it. When I switch back to hdmi, everything is normal again.
Where should I look?
TIA

mary@mythbox:~$ inxi -Fxxxrz
System:
Kernel: 5.8.0-50-generic x86_64 bits: 64 compiler: N/A
Desktop: Cinnamon 4.8.6 wm: muffin 4.8.1 dm: LightDM 1.30.0
Distro: Linux Mint 20.1 Ulyssa base: Ubuntu 20.04 focal
Machine:
Type: Desktop System: Gigabyte product: B550M DS3H AC v: N/A
serial: <filter>
Mobo: Gigabyte model: B550M DS3H AC v: x.x serial: <filter>
BIOS: American Megatrends v: F10 date: 09/18/2020
Battery:
Device-1: hidpp_battery_0 model: Logitech Wireless Mouse M325
serial: <filter> charge: 55% (should be ignored) rechargeable: yes
status: Discharging
Device-2: hidpp_battery_1 model: Logitech Wireless Keyboard K360
serial: <filter> charge: 100% (should be ignored) rechargeable: yes
status: Discharging
CPU:
Topology: Quad Core model: AMD Ryzen 3 PRO 4350G with Radeon Graphics
bits: 64 type: MT MCP arch: Zen rev: 1 L2 cache: 2048 KiB
flags: avx avx2 lm nx pae sse sse2 sse3 sse4_1 sse4_2 sse4a ssse3 svm
bogomips: 60684
Speed: 1397 MHz min/max: 1400/3800 MHz boost: enabled Core speeds (MHz):
1: 1336 2: 1385 3: 1225 4: 1600 5: 1273 6: 1301 7: 1247 8: 1537
Graphics:
Device-1: AMD Renoir vendor: Gigabyte driver: amdgpu v: kernel
bus ID: 0a:00.0 chip ID: 1002:1636
Display: x11 server: X.Org 1.20.9 driver: amdgpu,ati
unloaded: fbdev,modesetting,vesa resolution: 1920x1080~60Hz
OpenGL: renderer: AMD RENOIR (DRM 3.38.0 5.8.0-50-generic LLVM 11.0.0)
v: 4.6 Mesa 20.2.6 direct render: Yes
Audio:
Device-1: AMD driver: snd_hda_intel v: kernel bus ID: 0a:00.1
chip ID: 1002:1637
Device-2: AMD Family 17h HD Audio vendor: Gigabyte driver: snd_hda_intel
v: kernel bus ID: 0a:00.6 chip ID: 1022:15e3
Sound Server: ALSA v: k5.8.0-50-generic
Network:
Device-1: Intel Wireless-AC 9260 driver: N/A bus ID: 07:00.0
chip ID: 8086:2526
Device-2: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet
vendor: Gigabyte driver: r8169 v: kernel port: f000 bus ID: 08:00.0
chip ID: 10ec:8168
IF: enp8s0 state: up speed: 100 Mbps duplex: full mac: <filter>
Drives:
Local Storage: total: 1.36 TiB used: 600.98 GiB (43.0%)
ID-1: /dev/nvme0n1 vendor: Samsung model: SSD 970 EVO Plus 500GB
size: 465.76 GiB speed: 31.6 Gb/s lanes: 4 serial: <filter> rev: 2B2QEXM7
scheme: MBR
ID-2: /dev/nvme1n1 vendor: Samsung model: SSD 970 EVO Plus 1TB
size: 931.51 GiB speed: 31.6 Gb/s lanes: 4 serial: <filter> rev: 2B2QEXM7
scheme: MBR
ID-3: /dev/sda type: USB vendor: Western Digital model: WD10 01FALS-00J7B1
size: 931.51 GiB serial: <filter> scheme: MBR
Partition:
ID-1: / size: 213.34 GiB used: 13.67 GiB (6.4%) fs: ext4
dev: /dev/nvme0n1p7
ID-2: /home size: 483.34 GiB used: 71.50 GiB (14.8%) fs: ext4
dev: /dev/nvme1n1p4
Sensors:
System Temperatures: cpu: 34.9 C mobo: N/A gpu: amdgpu temp: 28 C
Fan Speeds (RPM): N/A
Repos:
No active apt repos in: /etc/apt/sources.list
Active apt repos in: /etc/apt/sources.list.d/official-package-repositories.list
1: deb http://mirror.cs.jmu.edu/pub/linuxmint/packages ulyssa main upstream import backport
2: deb http://mirror.cs.jmu.edu/pub/ubuntu focal main restricted universe multiverse
3: deb http://mirror.cs.jmu.edu/pub/ubuntu focal-updates main restricted universe multiverse
4: deb http://mirror.cs.jmu.edu/pub/ubuntu focal-backports main restricted universe multiverse
5: deb http://security.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
6: deb http://archive.canonical.com/ubuntu/ focal partner
Info:
Processes: 318 Uptime: 3m Memory: 15.11 GiB used: 2.10 GiB (13.9%)
Init: systemd v: 245 runlevel: 5 Compilers: gcc: 9.3.0 alt: 9 Shell: bash
v: 5.0.17 running in: gnome-terminal inxi: 3.0.38

[Moonstone Man]

Where should I look?

The DVI cable and the connections to the monitor and the machine.

The symptoms you describe are typical of a bad connection, but at worst, it could be a faulty port on your machine.

[JTJersey]

What can you tell us about the monitor that replaced your wife's monitor that she took back? Do you have any other types of ports available? VGA perhaps?

[linuxgrrl]

Thank you!! In the process of looking at the monitor for different ports, I saw that the cable had indeed come slightly loose on the monitor side. I had been looking at the computer side, assuming it was some fault of the new motherboard. So glad I was wrong!! Everything looks great now. Thank you!!