It's been quite some time since I've used only 2 cards for gaming on three screens. The last was the 680's but they had 2 DVI outputs.
 
My problem:  I just retired my 4 Titans and purchased 2 1080's.  I set them up last night running one DVI out from each card and attempted to use the Display Port as my 3rd surround output.  (My monitors are Yamakasi 1440p and ONLY have DVI input).  I used an "active" (but no power from USB) DP to DVI converter with no luck. (I believe this one came with the Titan)  I got 2 of the screens to work but not the 3rd.  Also, I could not get the Nvidia panel to appear on screen.  It was available when I right clicked on desktop but wouldn't appear.
 
I remember running my 290's and needed an Active, usb powered Mini DP to DVI connector, but that was AMD so I'm not sure.  I take it I will need the same now?  Last night, I ordered this:   https://www.amazon.com/gp/product/B00A493CNY/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
 
I searched in an attempt to find if the 1080 had support for dual mode display port (DP++) so I could use a passive adapter but I came up empty and with how things went last night, I take it they do not.
 
So, I defer to the surround/display experts.  What say ye?  Thanks for your help!

Thanks for the reply..The first thing I did was refer to that page as I know that the connection requirements change from card to card.  I would be using option 5 or 6:



 
 

That adapter should do the trick. I would have recommended this one... https://www.amazon.com/Ac...ion*=1&*entries*=0

Nope, no luck.  Did nothing. Only one screen (DVI from card 1) is live.  Now, the option in the panel is there and looks like it will work, but nothing happens, the other two screen stay black with no signal.

Sajin
I thought you had two screens working?

I did.  Now only one is.  I'm going to run Display Driver Unistaller to see if that helps.  Seems like a software problem of some sort.

I'm guessing you tried other dp ports too?

I have 3 of those adapters that Sajin link and they do work. I havent had any issues with them, so its possible you got a bad one.  Did you make sure to plug the USB cable in to a USB port that has the correct drivers installed?  I had plugged mine into an add-in card and they didnt work until i installed the driver for the USB 3.1 ports.  I assume you are using an SLI bridge as well?

Perhaps I should shop for one 27" 1440p monitor with a DP input ;)  
 

Sajin
You probably got a bad adapter. Hopefully the one I linked will work better for ya.

Thanks Sajin, I very much appreciate your help.  I'll get the Accell adapter on Thursday and will post my results.

Well, my post about a new monitor was somewhat of a joke.  Then I thought a bit more about it and purchased one.
 
All three screens active, no real problems.  Probably better anyhow.  The Yamakasi Catleap's were awesome 3 years ago for the price, but with DVI only input they make life a little hard.  I'm going to pick up two more new 27" monitors when I can afford it.  Thanks for the help again.