Zombie thread alert. Well, I need help now and this was the best thread, so...
OK.
Just got 3 of the new lovely Dell U2515H panels (2560x1440). Got them all set up OK but the right hand panel (3) is all fuzzy. Panels 1 & 2 (centre & left) are absolutely gorgeous.
The fuzziness on the right hand panel seems to be because it has a max available resolution of 2048x1152. It's not at its native res. Windows won't let me set it any higher and nor would the NVidia thing. So I've created a custom setting in the driver for the right resolution and it's scaling up to it. I think that this is where the fuzziness is coming from.
Please note that I'm not intending to play ED spanned across three panels just yet. I know that'll take more GPU power than I have.
So, is there any way I can get them all at 2560x1440 for normal desktop use?
If not, what is the issue?
There are plenty of things you can do to find the problem.
first off swap the cables to monitors 2/3 around - you don't even have to move the monitors - and see if the problem moves.
Note that 3 x 2560x1440 is a hell of a lot of pixels - I only have 3 x 1600 x 1200 and that has always streched the video connectivity options.
I'd recommend you connect the monitors independently to the graphics card (there must be a reason you didn't do this, maybe it's the card or you just wanted one neat cable). But just swap the fuzzy one onto a regular dual-dvi / vga connection.
Maybe one of your DP cables is more crap than the others - try swapping those around.
Anyhoo, 3x2560x1440 down a single cable *is* state-of-the-art, regardless of the theoretical capabilities of DP, so it doesn't surprise me you're having problems.
FYI I have my monitors in portrait mode, so the 3x isn't too letterbox. Works well for ED, with 2 x 660Ti in SLI (with a lot of low graphics settings though).