Same issue with Dell P4317Q GTX 960 with nvidia-370 drivers on Ubuntu 16.04. 

One thing that I can be sure is, it is only happening when you connect the screen with display port. It happens with or without nvidia drivers. Looks like it is linux kernel or ubuntu desktop issues. 

The screen blacks out occasionally and comes up on immediately.  I hope below helps.

adel@Adel:~$ uname -a
Linux Adel 4.4.0-62-generic #83-Ubuntu SMP Wed Jan 18 14:10:15 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
adel@Adel:~$ sudo lshw -short
H/W path           Device       Class          Description
==========================================================
                                system         Z170MX-Gaming 5 (To be filled by O.E.M.)
/0                              bus            Z170MX-Gaming 5
/0/0                            memory         64KiB BIOS
/0/3d                           memory         128KiB L1 cache
/0/3e                           memory         128KiB L1 cache
/0/3f                           memory         1MiB L2 cache
/0/40                           memory         8MiB L3 cache
/0/41                           processor      Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
/0/42                           memory         32GiB System Memory
/0/42/0                         memory         8GiB DIMM Synchronous 2133 MHz (0.5 ns)
/0/42/1                         memory         8GiB DIMM Synchronous 2133 MHz (0.5 ns)
/0/42/2                         memory         8GiB DIMM Synchronous 2133 MHz (0.5 ns)
/0/42/3                         memory         8GiB DIMM Synchronous 2133 MHz (0.5 ns)
/0/100                          bridge         Sky Lake Host Bridge/DRAM Registers
/0/100/1                        bridge         Sky Lake PCIe Controller (x16)
/0/100/1/0                      display        GM206 [GeForce GTX 960]
/0/100/1/0.1                    multimedia     NVIDIA Corporation
/0/100/1.1                      bridge         Sky Lake PCIe Controller (x8)
/0/100/1.1/0       wlp2s0       network        Wireless 7260
/0/100/14                       bus            Sunrise Point-H USB 3.0 xHCI Controller
/0/100/14/0        usb2         bus            xHCI Host Controller
/0/100/14/0/5                   bus            USB5734
/0/100/14/0/5/3                 bus            USB3.0 Hub
/0/100/14/1        usb1         bus            xHCI Host Controller
/0/100/14/1/5                   bus            USB2734
/0/100/14/1/5/2                 multimedia     Logitech Webcam C930e
/0/100/14/1/5/3                 bus            USB2.0 Hub
/0/100/14/1/5/3/2               input          USB Receiver
/0/100/14/1/5/3/3               multimedia     USB Multimedia Audio Device
/0/100/14/1/5/3/4               input          MECH
/0/100/14/1/5/5                 input          Hub Controller
/0/100/14.2                     generic        Sunrise Point-H Thermal subsystem
/0/100/16                       communication  Sunrise Point-H CSME HECI #1
/0/100/17                       storage        Sunrise Point-H SATA controller [AHCI mode]
/0/100/1b                       bridge         Sunrise Point-H PCI Root Port #17
/0/100/1b.2                     bridge         Sunrise Point-H PCI Root Port #19
/0/100/1b.2/0      enp4s0       network        Killer E220x Gigabit Ethernet Controller
/0/100/1c                       bridge         Sunrise Point-H PCI Express Root Port #1
/0/100/1c/0                     bridge         Intel Corporation
/0/100/1c/0/0                   bridge         Intel Corporation
/0/100/1c/0/1                   bridge         Intel Corporation
/0/100/1c/0/2                   bridge         Intel Corporation
/0/100/1c/0/2/0                 bus            Intel Corporation
/0/100/1c/0/2/0/0  usb4         bus            xHCI Host Controller
/0/100/1c/0/2/0/1  usb3         bus            xHCI Host Controller
/0/100/1c/0/4                   bridge         Intel Corporation
/0/100/1c.4                     bridge         Sunrise Point-H PCI Express Root Port #5
/0/100/1d                       bridge         Sunrise Point-H PCI Express Root Port #9
/0/100/1d.4                     bridge         Sunrise Point-H PCI Express Root Port #13
/0/100/1f                       bridge         Sunrise Point-H LPC Controller
/0/100/1f.2                     memory         Memory controller
/0/100/1f.3                     multimedia     Sunrise Point-H HD Audio
/0/100/1f.4                     bus            Sunrise Point-H SMBus
/0/1               scsi5        storage        
/0/1/0.0.0         /dev/sda     disk           1TB ST1000LM014-1EJ1
/0/1/0.0.0/1       /dev/sda1    volume         243MiB Linux filesystem partition
/0/1/0.0.0/2       /dev/sda2    volume         931GiB Extended partition
/0/1/0.0.0/2/5     /dev/sda5    volume         931GiB Linux LVM Physical Volume partition
/1                              power          To Be Filled By O.E.M.
/2                 veth743011d  network        Ethernet interface
/3                 veth3028c7b  network        Ethernet interface
/4                 vetha374364  network        Ethernet interface
/5                 veth5ed037e  network        Ethernet interface
/6                 vethbb05654  network        Ethernet interface
/7                 veth75114f0  network        Ethernet interface