Does the monitor work elsewhere?
Re: grab a small video card and try?
Only if you already have one. Test with what you have around. Depends on what type of monitor inputs you have, try different cables, adapters. I use Dell adapter, but a basic adapter would work as well.
If you are connecting to a 4K TV using HDMI cable, check your TV settings to see if you can change HDMI to enhanced mode and try both HDMI2 or HDMI3.