I've got a Dell S2716DG with a 980Ti Hybrid.  I've got the monitor running at 2560x1440 at 144Hz with G-Sync on.  When I scroll, move windows around, and on moving images I see some noticeable ghosting.  I've been going back and forth with Dell trying to solve this and so far no solution.  One thing they did say is that the S2716DG requires (as specified by NVIDIA) a pixel clock of at least 586 MHz.  The NVIDIA control panel is indicating the current pixel clock is 569.844 MHz, lower than what Dell/NVIDIA is specifying.  I didn't see a good way to change the pixel clock in the NVIDIA control panel.  I did try changing the value in Precision but the pixel clock slider is already all the over to the right.  And manually changing the pixel clock field to 586Mz doesn't appear to result in a compatible display setting (screen goes black and after a few seconds reverts back).  And in Prevision the pixel clock field is at 560 MHz (so not the same as what the NVIDIA control panel is telling me a t 596.844 MHz.)
 
So a couple of specific questions.
1) Anyone know if I need the 586 MHz pixel clock to to run 1440 at 144 Hz?
2) Is there a way to overclock the pixel clock on the 980Ti outside of the NVIDIA control panel and Precision (some other setting I'm missing/something needs to be unlocked)?

If I go to custom resolutions and try to create a custom resolution there is a Pixel clock reported in the bottom right hand corner.  Can't seem to modify the timing to get the clock Dell is stating is necessary.

PG278Q is an IPS monitor, right?  The 2716DG is a TN panel.  No idea if that makes any difference.  

So sounds like the pixel clock doesn't really matter.  So no idea where Dell got this spec from.  
 
They've already sent a replacement monitor and I'm seeing the same issue.  (Maybe that's why these were refurbs) Done a bunch of troubleshooting with no good results.  Wonder if it's some interface on the DVI cable.

Whoops, I meant Displayport.  Only DP and HDMI inputs on the monitor and Gsync/144Hz doesn't work over HDMI (unless I's missing something).  (Still get ghosting at lower refresh rates over HDMI as well.)

I've got three, two from Dell and a Monoprice one I just got yesterday.  I'm going to swap them around tonight.  I've also got my old IPS monitor that I have yet to test with.  Won't get 144Hz, but I can least see if I get ghosting at 60 Hz.

Hey,
I had this issue with the 1080 class cards now downclocking on the desktop when it was set to 1440 mode on my Dell monitor at 144hz. The way to fix it is set your desktop to 120hz, and in global profiles to let the 3d stuff run at highest speed possible which lets them run at 144hz. Then in PrecisionX, set the slider from 120hz to 144hz and you'll see the pixel clock will move up to the right number. This compensates for the NVidia driver problem that's been around for years now for this resolution on their cards at 144hz. Then you'll have 144hz all the time and your card won't stay in graphics mode on the desktop when it's not doing anything 3D.

Hey,
 
Yeah it's an old problem, and so specific to 1440 mode at 144mhz and the 1080 and TI series not kicking out of graphics mode on the desktop. You can run the 120hz desktop, but to get it to 144 you really need PrecisionX to change it, then if you select 144 in Nvidia control panel it's perfect and will go into the 2D clock speeds. I found the thread on the first page of Google when searching for something else with setting up the 1080TI Black Edition, but thought I'd mention it since more people are running that mode and their cards won't slow down.

Hmmm.
I am wondering if that may be why I was having so many issues before, when I was running 144hz?
Someone said to do 120hz instead, and I have, and I still have issues but not 'as bad' as before.
 
I also just got loaned some money, and bought a new, certified, 1.3 DP to DP cable. I hope that fixes the rest of the issues for me, but I doubt it. There are just TOO many issues I am having with the titan x for it to be just a cable.
Right?
RIGHT?
ROIGHT?!?!?!?!
Hehehe.