New owner of BenQ XL2420Z - For the love of god, please help

[DukeLaze]

Hello there!
So I just got my BenQ XL2420Z monitor...
And HOLY SH*T does it blow...

I knew the colors wouldn't be too good, but this is horrible.

But that isn't the main problem... Here it is. I connected using a DP cable, supports 144Hz, all good and dandy.
After starting using this monitor, EVERYTHING lags/stutters. Browsers, moving windows around etc.
Everything except for games, and the mouse when I'm not dragging any windows around.

Have anyone experienced this? Is there a fix? I can actually live with the terrible colors (hell I might even be able to change it with Windows color profile + the screen settings themselves) but I can not live with this lag...

My setup:
i7 3770k OC 4Ghz
MSI GTX 680 Twin Frozr III 2GB (Core OC 63Mhz, Mem OC 400Mhz)
Gigabyte GA-Z77X-UD3H
OCZ Agility 4 SSD
Corsair Vengeance DDR3 1600MHz 16GB CL8

Monitors:
BenQ XL2420Z 60hz/120hz/144Hz 1080p
Toshiba TV 60Hz 1080p
Crappy Syncmaster 60hz/75Hz 720p (Switched for BenQ XL2420Z)
Some old Acer 60Hz (old main screen) 1080p

Never experienced something like this before...

I've tried:
Different refresh rates
Driver upgrade/Downgrade
Different "modes" on the XL2420Z

*HEEEEEEEEEEEEELP*

[DukeLaze]

Little update:
When I disable the BenQ (and only use my Acer monitor) the extreme stutter goes away, and the good old 60Hz "normal" stutter is there (I/e if I move a window quickly, it isn't smooth)

[flood]

try using the benq monitor by itself.
i've had the same issues when using two monitors and moving a window between the boundary of the two.

[Ranzear]

Something very important to note: Setting 120hz+ refresh rate and 1080 in NVidia control panel often sets the color depth to 16-bit, even though it doesn't need to be. My 2411z, very same panel, matches well enough my ASUS IPS display in colors and brightness with the ICC profile for the 2420z.

Double check you didn't notice it getting bumped down, and/or go check gradients on lagom.nl. This is another good reason for VT1350 custom resolution, because you can force the color depth too.

I have a lot of the same stuttering going on with my dual monitor setup, but I think it's mostly 2D stuff that it happens with. I should go make a 120/144hz WebGL test I think...

[Labo]

I got rid of my stuttering (dual monitor setup with a Dell 2007WFP, had terrible stuttering on 2d elements during the first minutes) as soon as I manually applied the XL2420z driver that came in its CD (Windows 7 only applied a generic PnP driver to it). It's now smooth on both screens and even if you keep a selection box on both of them at the same time. Also, in case this is relevant, my monitor is using firmware v3.

[Chief Blur Buster]

Temporarily disconnect your Acer monitor -- and see what happens.
Also, try making the 144Hz the primary monitor (even if it's not the center monitor)

There is often strange interactions between a 144Hz monitor and a 60Hz monitor, ESPECIALLY when moving windows between them & stretching windows between both of them. Also, Windows 8 plays better with multi-refreshrate situations so that may be worth looking into.