You need to disable the onboard graphics card in the bios.
Thanks for your reply. How exactly is this done. Is this a common problem with laptops that have this dedicated video card?
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Reducing the resolution of my ASUS notebook's 4k display to 1920x1080, adjusting the W10 scaler to 125%, and going to NVIDAS and INTELs direct download site and updating the two ASUS graphic display drivers was tried.
Either the three things or a combination did the trick! Note: I had previousll updated the drivers thru ASUS's website latest driver uploads utility, but read that drivers should always be uploaded directly from the Manufacturer's websites.
4K test videos were edited in Prem El and exported to 4k without a hitch.
Crossing my fingers that I have been able to solve the problem