second creen does not wake up after having been powered off


I am using a Dell Precision Tower 5810 with an NVIDIA Corporation GM206GL [Quadro M2000]. The OS is CentOS 7.5.1804. I am using the NVidia driver v390.87 installed from the Elrepo repoitory and updated through yum with the whole OS.

I have had a single screen DELL P2717H for many months, and all went well. Recently, I have added second screen on my left : a Samsung SyncMaster 204B, but I am declaring in NVidia settings the Dell screen (in front of me) to be the primary screen. The screens are connected through DisplayPort.

When I leave the office at the end of the day, I power off both screens (with their power button). When I come back in the morning and power on both screens, the locked desktop is displayed on the Samsung, but the Dell is always in power save, and the desktop does not show up; the only reliable and quick way I have to wake it up is to start nvidia-settings, where I always see its resolution being “Off”, and I change it to “Auto”.

During the day, if I am away from my office for a long time, sometimes the Dell is in power save and stays in this state, or does not; sometimes even in the morning, the Dell screen wakes up by itself, but this is very rare. So this behavior seems to have some randomness.

Is there anything I can do to definitely fix this annoying issue ?

Best regards
R. Grasso