hp mini 400 g2, DP issue

Hi

I have a problem with 4k display and HP ProDesk 400 G2  mini (i3-6100t). The maximal resolution 3840x2160 at 60Hz is causing the flickering. The flickering is seen in the linux system and also in the BIOS. The 4k display works with the same DP cable on different PCs  at full resolution and refresh rate. If I set a lower refresh rate 3840x2160 at 30Hz display works, usually I change the DP1.2 to version 1.1. I have the latest graphic drivers. I have seen there have been many problems with DP1.2 and 60Hz also by other manufacturers, usually a bios update solved the problems. When can I expect the new bios, if this is the case?

My monitor is AOC U2868Pqu.

With best regards

Andrej