I have a GTX 980 as well, and my issue is that the entire display flickers and blacks out randomly when using/viewing certain abilities (as a MNK, Twin Snakes causes it to happen most often). Affects both monitors, almost as if it's resetting the display or changing resolution on the fly - everything keeps happening in the background as it should. All display modes (windowed/borderless/FS) and several resolutions tested as well as all graphical pre-sets and individual graphics options - nothing helps. DX9 client runs just fine.

-=-=-=-=-=-=- System Information -=-=-=-=-=-=-

SYSTEM_OS Windows 7 Professional 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.150525-0603)
SYSTEM_CPU Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz (8 CPUs), ~4.0GHz
SYSTEM_CORE_NUM SYSTEM_CORE_LOGIC 8 SYSTEM_CORE_PHYSICS 4
SYSTEM_BIOS BIOS Date: 10/01/14 21:24:56 Ver: 20.12
SYSTEM_LANGUAGE English (Regional Setting: English)
SYSTEM_MEMORY 16324.234MB
SYSTEM_VIRTUAL_MEMORY 2047.875MB
SYSTEM_PAGE_FILE 40898.441MB
SYSTEM_STORAGE C:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 465.636GB SYSTEM_FREEDISC_SPACE 371.812GB
SYSTEM_STORAGE D:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 2794.282GB SYSTEM_FREEDISC_SPACE 2239.889GB
SYSTEM_STORAGE F:\ SYSTEM_HARDDISK_DRIVE SYSTEM_TOTALDISC_SPACE 167.554GB SYSTEM_FREEDISC_SPACE 143.459GB
SYSTEM_DIRECTX_VERSION DirectX 11
SYSTEM_GRAPHICS NVIDIA GeForce GTX 980
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY1
SYSTEM_GRAPHICS_CHIP GeForce GTX 980
SYSTEM_GRAPHICS_MAKER NVIDIA
SYSTEM_GRAPHICS_VRAM 3072.000 MB
SYSTEM_GRAPHICS_SHARED_VRAM 1023.938 MB
SYSTEM_GRAPHICS_DAC Integrated RAMDAC
SYSTEM_GRAPHICS_DISPLAY_MODE 1920 x 1200 (32 bit) (59Hz)
SYSTEM_GRAPHICS_DRIVER nvd3dumx.dll,nvwgf2umx.dll,nvwgf2umx.dll,nvd3dum,nvwgf2um,nvwgf2um
SYSTEM_GRAPHICS_DRIVER_VERSION 9.18.0013.5306
SYSTEM_GRAPHICS_DRIVER_DATE 5/28/2015 12:04:11 AM
SYSTEM_GRAPHICS_DRIVER_LANGUAGE English
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_GRAPHICS NVIDIA GeForce GTX 980
SYSTEM_GRAPHICS_DEVICE \\.\DISPLAY2
SYSTEM_GRAPHICS_CHIP GeForce GTX 980
SYSTEM_GRAPHICS_MAKER NVIDIA
SYSTEM_GRAPHICS_VRAM 3072.000 MB
SYSTEM_GRAPHICS_SHARED_VRAM 1023.938 MB
SYSTEM_GRAPHICS_DAC Integrated RAMDAC
SYSTEM_GRAPHICS_DISPLAY_MODE 1920 x 1080 (32 bit) (144Hz)
SYSTEM_GRAPHICS_DRIVER nvd3dumx.dll,nvwgf2umx.dll,nvwgf2umx.dll,nvd3dum,nvwgf2um,nvwgf2um
SYSTEM_GRAPHICS_DRIVER_VERSION 9.18.0013.5306
SYSTEM_GRAPHICS_DRIVER_DATE 5/28/2015 12:04:11 AM
SYSTEM_GRAPHICS_DRIVER_LANGUAGE English
3.0
SYSTEM_GRAPHICS_PIXEL_SHADER 3.0
SYSTEM_GRAPHICS_VERTEX_TEXTURE SYSTEM_SUPPORT
SYSTEM_SOUND Speakers (Realtek High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {199B3350-2BD3-41E6-9C47-CE26CE09B6DA}
SYSTEM_SOUND_DEVICE_NAME RTKVHD64.sys
SYSTEM_SOUND_DRIVER_VERSION 6.00.0001.7373
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 1/6/2015 6:43:52 PM
SYSTEM_SOUND Realtek Digital Output (Realtek High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {21A09D87-FA0D-4F30-B422-1119352F54E7}
SYSTEM_SOUND_DEVICE_NAME RTKVHD64.sys
SYSTEM_SOUND_DRIVER_VERSION 6.00.0001.7373
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 1/6/2015 6:43:52 PM
SYSTEM_SOUND ASUS MK241-C (NVIDIA High Definition Audio)
SYSTEM_SOUND_DEVICE_ID {BA7795CE-8EFD-4EAE-B49A-F05528E6A1BF}
SYSTEM_SOUND_DEVICE_NAME nvhda64v.sys
SYSTEM_SOUND_DRIVER_VERSION 1.03.0034.0003
SYSTEM_SOUND_DRIVER_LANGUAGE English
SYSTEM_SOUND_DRIVER_DATE 5/28/2015 12:04:11 AM
SYSTEM_INPUT {6F1D2B60-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Mouse
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 3 SYSTEM_GAMEPAD_BUTTON 8 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {6F1D2B61-D5A0-11CF-BFC7444553540000}
SYSTEM_INPUT_NAME Keyboard
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 0 SYSTEM_GAMEPAD_BUTTON 128 SYSTEM_GAMEPAD_FOV 0
SYSTEM_INPUT {F6A8C890-F1A2-11E4-8001444553540000}
SYSTEM_INPUT_NAME Logitech RumblePad 2 USB
SYSTEM_INPUT_REMARKS SYSTEM_GAMEPAD_AXIS 4 SYSTEM_GAMEPAD_BUTTON 12 SYSTEM_GAMEPAD_FOV 1