Hi,
 
I got this problem just right now.
 
I put my PC in to sleep then when I'm trying to wake it up, I just get a blank screen though the lights of the PC were on. So I tried several restarts until I finally change ports, HDMI and DVI works great but when I use DisplayPort, I get no signal.
 
I checked Nvidia Experience and saw an update (320.49 Beta), thinking maybe I need to update to that driver to fix it but it was working well with 314.22 and 320.18 drivers. I also don't want to try Betas.
 
Any thoughts?
 
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EDIT:
 
I forgot to mention.
 
When I'm using DisplayPort, I can get pass through "Starting Windows (Windows logo)" screen but after that, at the time where I need to login, DisplayPort signal will be lost and my monitor will go to sleep after few seconds. Only HDMI and DVI works..

I am downloading it now. Should I do a clean install or just let Nvidia Experience work it by itself? Thanks!

I will try and give an update later. Thanks a lot!

Do you have another DP cable you can try?
I just had one go bad causing strange issues with my monitor.

I hope that's all it is.
I was about to send my monitor back until I tried another cable.

It's really sounding like a bad cable, I would get a new cable. If it doesn't work from their maybe RMA could be a bad DP port on card.

I have this exact same problem, how can it be the cable when DP is recognized during boot? I only have this problem since upgrading to Windows 8.1 preview. I'm running a GTX 780 I should add.
 
Tried beta 8.1 preview driver from Nvidia and non-betas when that didn't work. :/

I thought that might be the case. Typically I have run my TV via HDMI connected only to the GPU, not the TV and then the DP to my monitor. However, I thought of trying to unplug the HDMI from the GPU and that didn't seem to work. What I've found is it's definitely something going on with the driver because refreshing the OS DP is fine UNTIL you install the nvidia driver.

I have the same problem. It's not the port or cable as it works during boot. It is Windows drivers not properly recognizing displayports!. I found this solution elsewhere. Give it a try:
 
Description of Solution: It is honestly as if the driver install the first time happens incorrectly and then it doesn't do plug n play correctly thereafter. So I tell device manager to show me nonpresent devices and then i uninstall them. The next time it connects it will redo the plug and play.
Solution that worked for me:

1. Click Start > Run.
2. Type cmd and press Enter.
3. At the command prompt, run this command: Note: In Windows 2008 and Windows 7, open the command prompt using the Run as Administrator option.
   set devmgr_show_nonpresent_devices=1 Note: If this command does not work (a possibility in Windows Server 2000 and 2003), you may need to add the parameter to Windows and set its value:
   1. Right-click the My Computer desktop icon and choose Properties.
   2. Click the Advanced tab and select Environment Variables.
   3. In the System variables section, click New.
   4. Set the Variable name to devmgr_show_nonpresent_devices and set the Variable value to 1 to enable the parameter.
   5. Click OK to add the variable to Windows.
4. Start the Device Manager by running this command from the same command prompt:
   start devmgmt.msc
5. Click View > Show Hidden Devices.
6. Expand the Monitors tree (click the plus sign next to the Monitors entry).
7. Right-click the dimmed Monitors, then click Uninstall.
8. Once all of the grayed out Monitors are uninstalled, reconnect your monitor.

This worked for me. Thanks you!

. Thank you so much. i didn't know what had happened. big thumbs up to you.