Thanks for posting, and thanks for the great information about your setup and the behavior you are seeing.
Looking at the manual for your Dell monitor here -> http://downloads.dell.com/manuals/all… on page seven it shows that this particular display requires a dual-link DVI connection in order to work. Our UGA-4KHDMI adapter’s output does not support being converted to a dual-link DVI video signal and we do our best to point this out in the forth information bullet of our Amazon product page -> http://amazon.com/dp/B00NQCFXGA.
Unfortunately that means our adapter won’t be a good solution for your monitor (in fact none of our products support dual-link DVI). All is not lost however as we offer a 30-day no-hassle return policy on all of our products sold by Plugable Technologies and shipped by Amazon using the automated system here -> http://amazon.com/returns
Please let me know if that information helps!