With a Dell P2715Q connected to an Asus Radeon R9 290 OC 4GB, I get the following error messages:
The system has detected a problem with the connection between your computer and the DisplayPort display that will prevent you from using the highest resolution and/or refresh rates.
The system has detected a link failure and cannot set the requested resolution and refresh rate on your DisplayPort display. Your display might not support the requested resolution or there may be an issue with the cable connecting the display to your computer.
That happens when I use a StarTech cable
StarTech.com
3M DisplayPort 1.2 CABLE
With that cable I can only ready 30 Hz.When I use the Dell provided I can set the max resolution at 60Hz. However then the screen becomes black making it unusable.
<bad link>