This is the first time I've ever decided to post a piece of advice to any website/message board because I think it would really help a lot of people. I had the exactly same problem after installing a new motherboard. I tried everything I could think of and all the tips I found online; to list just a few: updating my BIOS, reinstalling Windows 10, changing from DP cable to HDMI, reinstalling all my drivers, reinstalling just graphics drivers, plugging and unplugging my Nvidia graphics card several times, cleaning/vacuuming every single component (my comp is as clean as a whistle - looks brand new, trying all kinds of combinations in BIOS settings, etc - nothing worked.
And here is how I SOLVED IT! After reading some unrelated advice about the "turn on fast start-up" function in Windows 10 and reading about how it can cause certain booting problems, I thought I might as well give it a try, nothing left to lose. So, I went to Control Panel/Power Options and under "change setting that are currently unavailable" turned off the fast start-up. Voila, problem solved! I'm guessing there is was kind of incompatibility between my motherboard (Intel Desktop Board DQ77MK) and this particular Windows setting. After spending a week dealing with this issue and going out of my ever-loving mind, you can imagine my relief. I'll make sure to post this advice on as many message boards I can to help other miserable souls like myself.