I was disappointed to find that half of the monitors and TVs I tested don't show 640x480 HDMI though all of them worked at 1280x720. So I am redoing a project

I was disappointed to find that half of the monitors and TVs I tested don't show 640x480 HDMI though all of them worked at 1280x720. So I am redoing a project I am working on to use the higher resolution.