EDIT: I now strongly prefer the EW3270U over the EW3280U for my eye comfort. However, what works for me may not work for you!
All this time I thought old Nvidia cards were the best. Been using those. Then I got a laptop with Intel UHD 630, and on my favourite Windows 10 2015 LTSB (seriously, if you’re still messing about on post-1511 Windows 10 and having pain, switching to Simplixed Windows 7 or Window 10 2015 LTSB, which both still get security updates, is probably the most impactful thing you can do) it is has less pain than any Nvidia card I’ve tried in recent memory (including what I thought was a “safe” card, my GTX 650 Ti Boost).
Recently, decided to try the Intel HD 530 on my Skylake desktop. Holy bananas, it’s like looking at paper in combination with my BenQ EW3280U (Quantum Dots on the backlight dramatically reduce light spectrum associated pain for me). Unfortunately it can’t output 4K to the monitor at 60 frames, so I’m using 1080p output (same on the UHD 630, since it’s so weak graphics, it’s even slow sometimes to keep up with the desktop environment at 4K, never mind games). Definitely an improvement over the UHD 630, which was an improvement over various Nvidia cards (I did try the dithering registry keys). I run ditherig with both. On the HD 530, it doesn’t look like I’m trying to look at something masquerading as 3D (which is what a lot of eyestrain feels like for me). It’s FLAT and easy to focus on. Driver for the HD 530 is 10.18.15.4279 (WDDM 2.0 in this Windows 10 Threshold environment, sometimes Intel driver installers will install different WDDM driver from the SAME binary based on your Windows version, even between different Windows 10 versions), as recommended by @Sunspark.
Unrelated, but after a decent amount of experimentation, Windows 10 2015 LTSB is BETTER than Windows 7 for me. Cleaner image. @Gurm mentioned a while back that pre-1607 Windows 10 had very clean rendering, maybe even better than Windows 7. This is my experience. I will never stop stanning 2015 LTSB on this forum.