4k Display connectivity problem

[UnnamedUser]

I have a 4k Display of Sharp which works on some devices - but on most it doesn't. I have no idea what causes that behaviour.

The display:
- connected to DP 1.2 (according to spec of the display) as additional device (same behaviour when connected as primary / only display)
- background is lit when connected
- windows 7 recognizes the display correctly and shows it's running its native resolution and hz
- within MS Windows you can move your windows around and position them on the 4k display
- but the display remains black, shows no image at all

The display works on two machines:
- HP 850 G2: (Broadwell, Intel HD5500, i5 5300U)
- nVidia K2000, 320's driver, (Ivy Bridge, Xeon E5-1650 v2)

It doesn't work on those machines
- HP 850 G1: (Haswell, Intel HD4400, i7-4600U)
- nVidia GTX970 (340's, 350's, 360's drivers), i7-2600
- nVidia K2100M (320's, 340's driver), i7-4800MQ
- etc.

As you can see I tried a few PCs with various drivers. Those that work always instantly work (I didn't need to change anything on the system to make the display work from the beginning on).
I have no idea why it works on some machines and doesn't work on others. I'm especially confused by the old Ivy Bridge machine that is able to drive the display but the modern GTX970 isn't ...

Any idea what might cause that behaviour?

 

[UnnamedUser]

I just found out, it does work when I move the Quadro K2000 into the PC with the GTX970 (so I remove the 970 and put in the K2000). But it only works with the 320's driver, not with the new ones ..

What's that?! :/