Sorry if this is of no help but I feel I have to make a report on Dell monitors lately. Just to be clear, I've had 3 Dell monitors so far. All IPS models, touted to be catered for 'graphic-design' and 'professional' use. My final take on Dell monitors is they suck big time when it comes to colour accuracy. Despite the rave reviews and 5 star ratings, I experienced nothing but headaches trying to fix the colour cast on every model. I sorely blame it on their matte coating which introduces strange colour shifting. This is a well documented problem on the internet forums if you bother to search. To make things worse, if you don't have a colour calibration puck that can read a wide gamut monitor which most of the high end series are, you are so out of luck. Calibration can be quite a problem. I don't know the technical reason behind it but again it is also well documented.
So I bought a Apple Cinema Display and an iMac, calibrated them both and then I am done. Both look pretty close despite having different panels. Never had to look back or bother with colour calibration. Yes this might sound like an Apple advert but seriously I've had very little problems sending my artwork or photos to print either in the labs or printing at home. Colours are almost what I see on screen.
The conclusion is, stay away from any Dell 'pro' monitors especially the wide gamut one. If you have to buy them, please acknowledge its issues and if you need a fix, be prepared to make some expensive purchases to make things 'right'.
All right rant over.