Dual monitor setup using HDMI and DP not working.

[Sandburst Shower]

I have two Dell U2414H monitors currently connected via separate HDMI and DP cables to two separate HDMI and DP ports on my GPU. The problem is, once in a while, the monitor using the DP port either is disconnected right from startup, or gets randomly disconnected while working. The screen just goes black and the monitor shows "going to sleep mode" message, which in my monitor's case, is shown when it is connected right, but the PC is off.
What really confuses me is that the second monitor is recognized in the Nvidia control panel, but I can't tick the checkbox in front of it. It's not even grayed out. Windows device manager doesn't show the second monitor though. I tried the "extend these displays" in the windows display options, but it gives me a yellow colored warning saying "these settings could not be saved". The 2nd monitor shows up there right beside the first one, but I can't use it.
I usually got past this problem troubleshooting hardware and devices, the windows usually did something and asked me to reboot. But recently, I can't get the DP monitor to work in anyway, but uninstalling Nvidia Drivers and using the windows display driver. It works alright with windows display driver. Bad thing is, I have windows 10, and it downloads and installs Nvidia drivers automatically, as I found out today having Nvidia control panel in my right click menu on desktop. It could be fixed If I could stop windows from downloading the faulty drivers from Nvidia, but nope. Microsoft.

My rig:
Dell motherboard
Intel core i7-4770 CPU
16 MB XPS8700 DDR3 RAM
Asus strix Nvidia Geforce GTX 970 GPU
Green 700watt PSU
Dual Dell U2414H monitors, one connected via HDMI cable and the other with a DP-mini DP cable

Solution:
I never checked the ASUS for any fixes, and apparently my issue was a card specific issue.
Downloaded and installed the bios update for ASUS Strix GTX970.
This also fixed a strange issue I had with 3D apps and games like Skyrim for example, where I would get a blank screen after alt-tabbing to them, and I needed to restart my monitor to get image.

 

[James Mason]

Try the below first, but i'm wondering if maybe it's just bad cable, or the mini DP end is loose, because it doesn't have the teeth the full size DP cable has.

If you have graphics or driver issues, one of the most common fixes is a clean uninstall and removal of your graphics drivers.

To uninstall your drivers, first download and run Display Driver Uninstaller, and follow it's recommendations of booting into safe mode and ect.
(This is a direct download link so you don't grab the wrong version)
http://www.guru3d.com/files-get/display-driver-uninstaller-download,20.html

You'll download a compressed file called "[Guru3D.com]-DDU.zip"
Right click and choose extract.
Go into the folder and run the DDU v##.##.exe
This will extract more files to this folder.
Run Display Driver Uninstaller.exe
Choose Yes when it asks you to boot into SafeMode.
After you've rebooted into safe mode.
When DDU comes up, if it hasn't selected your GPU manufacturer (Nvidia/AMD/Intel) then choose it from the drop down list
Press the Clean and Restart option
If a window comes up asking to disable the Windows automatic installation of display drivers click yes.

After (or before removing the old drivers, just put the new ones on the desktop or somewhere handy) rebooting back into Windows, manually download the latest drivers from Nvidia or AMD, don't use auto detect, choose you GPU model and OS from the drop down lists.
Nvidia: http://www.nvidia.com/Download/index.aspx?lang=en-us
AMD: http://support.amd.com/en-us/download
Intel: http://www.intel.com/content/www/us/en/support/detect.html

 

[Sandburst Shower]

Try the below first, but i'm wondering if maybe it's just bad cable, or the mini DP end is loose, because it doesn't have the teeth the full size DP cable has.

If you have graphics or driver issues, one of the most common fixes is a clean uninstall and removal of your graphics drivers.

To uninstall your drivers, first download and run Display Driver Uninstaller, and follow it's recommendations of booting into safe mode and ect.
(This is a direct download link so you don't grab the wrong version)
http://www.guru3d.com/files-get/display-driver-uninstaller-download,20.html

You'll download a compressed file called "[Guru3D.com]-DDU.zip"
Right click and choose extract.
Go into the folder and run the DDU v##.##.exe
This will extract more files to this folder.
Run Display Driver Uninstaller.exe
Choose Yes when it asks you to boot into SafeMode.
After you've rebooted into safe mode.
When DDU comes up, if it hasn't selected your GPU manufacturer (Nvidia/AMD/Intel) then choose it from the drop down list
Press the Clean and Restart option
If a window comes up asking to disable the Windows automatic installation of display drivers click yes.

After (or before removing the old drivers, just put the new ones on the desktop or somewhere handy) rebooting back into Windows, manually download the latest drivers from Nvidia or AMD, don't use auto detect, choose you GPU model and OS from the drop down lists.
Nvidia: http://www.nvidia.com/Download/index.aspx?lang=en-us
AMD: http://support.amd.com/en-us/download
Intel: http://www.intel.com/content/www/us/en/support/detect.html

Things I've tried out so far:
- Using many different cables, all which work consistently with other devices. It didn't work. I don't think it's a cable issue.
- Switching monitors and DP ports, it didn't work so it can't be a port connectivity issue.
- Using Display driver uninstaller, windows driver uninstaller and the default Nvidia uninstall wizard to uninstall and install 3 different versions of Nvidia drivers. So far I've tried these versions: 390.65, 388.** and 344.**. The latter came in a CD with my graphics card.
- I download all drivers straight from the Nvidia site, specifying my GPU and using its recommendation, and even let it once recognize my GPU and download the best driver automatically.
I tried multiple other drivers on another system (I upgraded from a different MOBO, CPU, HDD, PS recently) which my GPU was used on before. It had the same problem.
- The only thing that ever gave me a consistent solution, was uninstalling Nvidia drivers a whole, and using windows' built-in display driver.
- Windows 10 won't let me stick with the built-in driver and It downloads and installs an Nvidia driver automatically (as of now It has downloaded the 388 version).
- I can connect my second monitor with 388 version of Nvidia drivers more than not, but it still randomly won't let me use my second monitor after some start ups.

 

[James Mason]

Try the below first, but i'm wondering if maybe it's just bad cable, or the mini DP end is loose, because it doesn't have the teeth the full size DP cable has.

If you have graphics or driver issues, one of the most common fixes is a clean uninstall and removal of your graphics drivers.

To uninstall your drivers, first download and run Display Driver Uninstaller, and follow it's recommendations of booting into safe mode and ect.
(This is a direct download link so you don't grab the wrong version)
http://www.guru3d.com/files-get/display-driver-uninstaller-download,20.html

You'll download a compressed file called "[Guru3D.com]-DDU.zip"
Right click and choose extract.
Go into the folder and run the DDU v##.##.exe
This will extract more files to this folder.
Run Display Driver Uninstaller.exe
Choose Yes when it asks you to boot into SafeMode.
After you've rebooted into safe mode.
When DDU comes up, if it hasn't selected your GPU manufacturer (Nvidia/AMD/Intel) then choose it from the drop down list
Press the Clean and Restart option
If a window comes up asking to disable the Windows automatic installation of display drivers click yes.

After (or before removing the old drivers, just put the new ones on the desktop or somewhere handy) rebooting back into Windows, manually download the latest drivers from Nvidia or AMD, don't use auto detect, choose you GPU model and OS from the drop down lists.
Nvidia: http://www.nvidia.com/Download/index.aspx?lang=en-us
AMD: http://support.amd.com/en-us/download
Intel: http://www.intel.com/content/www/us/en/support/detect.html

Things I've tried out so far:
- Using many different cables, all which work consistently with other devices. It didn't work. I don't think it's a cable issue.
- Switching monitors and DP ports, it didn't work so it can't be a port connectivity issue.
- Using Display driver uninstaller, windows driver uninstaller and the default Nvidia uninstall wizard to uninstall and install 3 different versions of Nvidia drivers. So far I've tried these versions: 390.65, 388.** and 344.**. The latter came in a CD with my graphics card.
- I download all drivers straight from the Nvidia site, specifying my GPU and using its recommendation, and even let it once recognize my GPU and download the best driver automatically.
I tried multiple other drivers on another system (I upgraded from a different MOBO, CPU, HDD, PS recently) which my GPU was used on before. It had the same problem.
- The only thing that ever gave me a consistent solution, was uninstalling Nvidia drivers a whole, and using windows' built-in display driver.
- Windows 10 won't let me stick with the built-in driver and It downloads and installs an Nvidia driver automatically (as of now It has downloaded the 388 version).
- I can connect my second monitor with 388 version of Nvidia drivers more than not, but it still randomly won't let me use my second monitor after some start ups.

Ah, apparently it's a known problem: https://forums.geforce.com/default/topic/928940/new-asus-strix-gtx-970-bios-update-fixes-black-screen-on-windows-login-screen-through-displayport/

Here's the proper site for the BIOS fix for your card:
https://www.asus.com/us/Graphics-Cards/STRIXGTX970DC2OC4GD5/HelpDesk_BIOS/