Desktop PC graphics hdmi to hdtv random flicker on off

Hi
I have desktop pc to hdmi on hdtv the screen flickers on off black for several seconds. Random times, 20 sec 120 sec 30sec 180 sec 50sec.
I have completley removed grapics driver using [Guru3D.com]-DDU installed newer graphics driver. I have tried with reccomended settings scale and layout 300% (rec) resolution 3840 x 2160 (also rec) in multiple displays I have tried duplicate and show only on 1 or 2. I'm not sure what relevent info may be helpful, some specs listed in info. Sorry if this is in the wrong section.

Thanks
P888

The HDMI interface for the GTX 750 Ti seems to HDMI 1.4a which does not support such resolutions and refresh rates.
You need HDMI 2 or more.

The TV may have an HDMI 2 input, but it is the lowest that is limiting i.e. the Graphics Card. No amount of driver fiddling will change that.

The answer is a newer Graphics Card that does support HDMI 2 or more.

The recommended resolution number just means that is the Panel pixels.

Thank you for the help, do you have any recomendations for a better graphics card that will work with my setup. What are my optipns for new vs good used one?

4k was first supported since HDMI 1.4 at 24hz only though so you have 1.4a so it will be a discrepancy with either your cable the rated HZ it can carry or the GPU/Monitor and the HZ etc, 750ti is pretty weak for 4k all though 750ti should be able to display the desktop and some light gaming at this resolution.

The monitor is probably taking like 30, 60 or 120 hz and it won't be 24hz because that is old. Try down clock your monitor to 24hz

It is up to you to look at options, the only thing I would say is something like GTX 1070 or newer variations would have HDMI 2.0 or better, check the detailed specs.
A used one is likely to have been hammered by a gamer.

Thanks for replys I do not have a clue what to buy as far as video cards go so thanks for the suggestion at least I have something to look for. Thanks to person who suggested 24Hz I have had no more black screens, plays beter than it did before.