people are reporting them not working well on these monitors
I have just got 2 dell u2711 monitors and i'm having issues with getting colours right
i just found this process on the internet today, gonna try it out today or tomorrow
Note: I didnt write this i just copy pasted from a forum i found on a google search
Step 1: Setting up the display.
Set the contrast to 100% and the brightness to 80%. Set the Gamma to (Mac), the Mode Selection to (Graphics), and the Preset Mode to (Custom Color). Now, in custom color leave the green at 100% and set both the Red and Blue to 98%.
Step 2: Setting up the Mac.
Run your Mac's Display Calibration Assistant (located in the Display section of System Preferences). Select the checkbox for Expert Mode and keep clicking continue till you get to the section with the lined boxes with the Apple logo in the middle.
Now, for all 5 'lined box' steps, make the Apple logo disappear using only the left slider (do not touch the right slider at all). To make the Apple logo disappear (blend into the box) you must squint your eyes until the lines that make up the box itself become one solid color (my eyes were about 75% closed). Take your time and make sure you are confident that the Logo is gone.
Then, when you come to the gamma screen either select 2.2 or 2.15 - the proper setting should be 2.2, however, I found the blacks to be not as deep as I'd like them to be (most likely because of the AG coating) so I choose 2.15 which I found to be the key to giving the display the richness it needs to look great.
When you get to the 'Target White Point' screen, select the checkbox 'use native white point'.
Then save you calibration profile and exit the assistant. Now go back to your Dell display settings and set the brightness to 100% and you should be good to go! Note: if you find your screen to be a little too dark, re-calibrate but try selecting 70% or 60% for the brightness during step one. That way, when you raise the brightness to 100% at the end, it should be somewhat brighter.
original link herehttp://forums.macrumors.com/showthread.php?t=1054380