Dull monitor, where to dig?

Question

Monitors

Good day to all! I've already broken my head, I can not understand what is the reason.
Relatively recently, I began to notice that the screen became less bright and less saturated, to the point that when you sit and read something or for a long time, your eyes start to hurt. The problem is that I can not understand what the problem is, in the monitor, or in the video card. I noticed that if you sit for a long time, the monitor starts to show more dimly, you can pull dvi and plug it back in, then the brightness becomes more or less. The most noticeable is the white color, it becomes not white, but with an admixture of yellow. Video card purchased a year ago nv 1050 ti. The monitor has only 2 dvi Vga inputs, on the video card hdmi, dvi, display port. I tried to connect via hdmi but with an adapter to dvi to the monitor, after a while the screen was dim again. Tell me where to dig?
While there are a few ideas, the video card, the monitor itself, well, the voltage

Answer 1

Not just voltage, but the voltage that the adapter holds under load, sometimes it is not enough, the backlight becomes dim and not uniform, although the rest of the electronics work fine ...
... the monitor will have to be disassembled and poked with a tester anyway

Answer 2

Generally! I got to the bottom of the problem, or rather I understood where the legs grow from.
Thank you all for your help!