Monitor enters power save mode

[voinealau]

The problem appears while using a Dell Precision 3510 in a docking station connected to two monitors and consists of one of the monitors going in a power save mode.
This happens in one of the following situation:
- the laptop goes to sleep
- I lock the laptop
- I open a Settings window. If the window was already opened and I just select it, everything is okay.
- I restart X (Alt+F2+r)
The only current solution I found for this, is to undock the laptop and dock it back in.
The following "solutions" I tried that did not work:
- restarting X (again)
- power cycling the monitor
- unplugging and plugging back the monitor
- changing resolution or order of monitors

I am currently using 17.04, but I had the same problem on 16.04.
Please let me know if you need additional information.
Regards,
Alex