I had this same problem. Are you using chrome? Is it 32bit chrome? Follow the link below for chrome but then click "Chrome for another platform" and then select chrome for 64bit windows https://www.google.com/chrome/browser/desktop/
Cleared it right up for me.
This is a good choice for that price range.
https://www.amazon.com/Samsung-U28E590D-28-Inch-LED-Lit-Monitor/dp/B00YD3DBOC
But I personally recommend you an IPS Monitor like the one I have due to the higher viewing angles and color accuracy
And of you like the second one and you want it with a better stand, there's a model called UD58-P.
Here is the one I got which ticks all the boxes I think: https://www.amazon.com/Philips-BDM4065UC-Resolution-Speakers-DisplayPort/dp/B00SCX78JS
Edit: It seems to have gotten a lot more expensive, I got it more than half a year ago for around 500 bucks, so if you can find a good deal for it I highly recommend it.
Any reason why I should doubt this adapter? This is what I bought.
What is PWM?
I have the Philips 40" which I like a lot. $800 on Amazon
If you mean "PoWer Management", it has not been an issue for me, though it does eventually time out with zero activity, though that's maybe just Windows power management, and not the screen itself. Also, when turning on my computer, the bios and boot sequence stuff all shows up on my secondary monitor. I'm not sure if that would show up on the 4K or not if that second monitor was not there.
The Philips is not perfect, though, so I would read the reviews. It's the best 40" option I know of, but does require some config to make sure you are running at 60Hz (it is terrible to use at 30Hz). The config involves making sure you are on DisplayPort, and then setting the monitor through it's awkward menus to use the newer version of DisplayPort.
Display wise, it is awesome. I am really happy I upgraded my old Dell 30-inchers.
I'm using it mostly for coding and work related stuff. I love the realestate, though I could see some people finding it a little bit big (not me though!). Gaming is also great on it, though for some games, even with my GTX980, I have to choose between 4K and lower settings, or higher settings and 1080p.