So I have an Asus 1440p monitor and 2 Samsung 1080p monitors.
 
For some reason I can only get the Asus to work if I plug it in via HDMI.  It still looks sharp and I am using a redmere 10.2 GB/s cable for it but I wanted to hook it up to the Displayport.  When doing so, windows and the nvidia software recognizes it is there, but when I enable it, I jsut get flashing for a few seconds then back to disconnected.
 
I can plug it in to the displayport if I unplug one of the other two monitors.  Just cannot figure it out, have used 3 different displayport cables that I verified are good, no help there.
 
It currently runs with one 1080P plugged into the display port with a DP to HDMI converter, the 1440p plugged in the middle HDMI slot (it is running in 1440p, looks good) and then a DVI-I to HDMI adapter to run the last monitor.  All on the same #1 card. 
 
Everything works fine in this setup and looks good, the redmere cables do make a difference (I had it running with a standard HDMI calbe and had framerate stuttering before) so I don't have any need to use the displayport, but I am curious as to what is going on.
 
Any ideas?

EVGATech_JoseR
schmake01 can you confirm what monitors are using what cables with what adapters so we can have a better idea where the problem could be?

 
 
When it does not work I am using
 
Display port:
Monoprice 6ft Premium DisplayPort 1.2 Male to Male Cable - Black (tried with 2 of these cables and the one that came with the monitor)
Product Number: 10582
to 
ASUS PB Series PB278Q
 
HDMI
Monoprice 15ft 10.2Gbps Ultra Slim Series High Performance HDMI® Cable w/ RedMere® Technology - White
 
 to
SAMSUNG B350 Series S27B350H
 
 
DVI
Monoprice DVI-D Single Link Male to HDMI® Female adapter
Monoprice 15ft 10.2Gbps Ultra Slim Series High Performance HDMI® Cable w/ RedMere® Technology - White
 
 to
SAMSUNG B350 Series S27B350H
 
 
 
When it does work:
Display port:
 Coboc CL-AD-DP2HD-6-BK DP DisplayPort to HDMI Passive Video Adapter Converter w/5.1 Channel Audio 
Monoprice 15ft 10.2Gbps Ultra Slim Series High Performance HDMI® Cable w/ RedMere® Technology - White 
to 
SAMSUNG B350 Series S27B350H
 
HDMI
Monoprice 15ft 10.2Gbps Ultra Slim Series High Performance HDMI® Cable w/ RedMere® Technology - White
 
 to
ASUS PB Series PB278Q
  
 
DVI
Monoprice DVI-D Single Link Male to HDMI® Female adapter
Monoprice 15ft 10.2Gbps Ultra Slim Series High Performance HDMI® Cable w/ RedMere® Technology - White
 
 to
SAMSUNG B350 Series S27B350H
 
The display port will work with the Asus IF I disconnect one of the Samsung monitors. It does not matter which one.