Custom Resolution @3840 × 2160 25hz impossible

Hi all

I bought my first 4K TV and tried to hook up the NUC DN2820FYKH.

First of all I'm running Win 7 on the NUC. In the Resolution window there's no option for 4K.

If I'm trying to use the Intel Graphics Panel there's no option for a custom resolution. Even with the "CustomModeApp.exe" trick it's not possible because I can't even launch this programm.

My Intel graphics Driver is: 36.15.0.1073

BIOS Version: 0045

At 25hz it should be possible even with HDMI v1.4 for a 4K resolution. I tried it with my notebook which has a dedicated Nvidia Geforce GT 650M and it works without any problems. The HDMI cable as well as the TV is NOT the problem.

Thanks in advance