I got a very similar problem.
Mini-HDMI > HDMI: 3840x2160@30Hz
Working if HDMI plugged in during Windows boot:
Mini-DP -> DP: 3840x2160@30Hz
Aim, but not working:
Mini-DP -> DP: 3840x2160@60Hz
Listing of Hardware:
-Asus PB287Q Monitor
-Lenovo Mini-DP to DP Cable P/N: 0B47091
All the hardware I used should be DP v1.2 compatible.
I don't get the Monitor to work, when I have it connected over DP during boot.
Installed is a Windows 10 Pro x64 (UEFI Mode)
-The latest graphics drivers https://downloadmirror.intel.com/25644/a08/GFX_Win7_8.1_10_64_184.108.40.20652.zip
-The latest chipset drivers https://downloadmirror.intel.com/25094/eng/Chipset_Win7_8_8.1_10_10.1.1.9.zip
and it still doesn't work.
Legacy mode is disabled in the BIOS.
In the video settings of the BIOS I tried both, to autodetect what type of monitor is attached and fix mode to DP, it didn't help.
What I tried else.
-I switched off the "Fast startup" option in Windows: Windows 10 Forums
To me it seems that if the display is connected over DP, then the UEFI firmware or GPU firmware, doesn't do a handshake with the display.
So not much suggestions, but same problem here.
Any suggestions or solutions from Intel?
No reply from Intel, but I found my problem; it was the cable. I had used a five meter cable so I bought a two meter cable (same brand) and everything worked as it should (3440x1440@60Hz). I got a three meter cable (again same brand), but that failed too, no picture at all. I googled I bit and it seems like displayport cables needs to be short.
This may not be your problem as you seem to get some picture at least, but if I were you, I would buy a high quality, short cable to eliminate that as a factor.
This message was posted on behalf of Intel Corporation
I’m sorry that it took me some time to come around to this post to be able to help you.
Did you try the latest Beta driver, you can download it here:
You can try checking with your monitor manufacturer to see if there is an INF file that you can install in your system; the INF file can help you solve display issues.
I also suggest accessing the Intel® HD Graphics Control Panel and once you have it open press <Ctrl><Alt>F8 to set graphics to default.
Do you have a high quality cable? If not, I suggest buying a high quality cable as
I hope this can help you.