Monitor flashes between hdmi and analog before turning off

[NekoRampage]

Hi
So I just moved houses and started setting up my pc again but hit a snag - when everything is plugged and switched on my monitor (Samsung curve monitor) stays blank even though my pc turns on and seems to run as normal, along with the blank screen it keeps switching from analog to hdmi and back again a few times before switching off completely.

I tried to use analog instead and the same problem occurs. I've also run it on a different monitor (Samsung syncmaster 943) using rgb instead and it won't even recognise it.

Pretty confused as it worked just yesterday. I'm not very savvy with computers so would rather not find out my graphics card is dead or something. Any help would be valued!

 

[Cycloid Torus]

Problems with video cards can be simple - like it worked loose in the slot (remove and reinsert) - it might be the 6 pin power connector (if you have one) has come loose (remove and reinsert) or, less likely, but still just marginally possible some other power connector.

If not fixed, try monitor on known good system. If monitor works properly (likely so) then it is the video card or the motherboard.

If none of that works for you, then it is time to borrower a known good video card to prove it isn't the slot on the motherboard.

If the second card works (motherboard slot is good) then it is very likely to be your video card.

 

[Cycloid Torus]

Another thought - if you have an internal video capability, it is possible that you need to confirm that the BIOS is set to use the PCI-e slot for video.

 

[Navin Talati]

Why bule thin vertical lines in the monitor (Samsung syncMaster B2230)?
It has happened during Upgrading Ubuntu 18-04 to 20.04