Hi Folks, I'm new to the forum, so apologies if this thread is similar to any others out there. I have searched but did not see anything resembling my issue. Just bought a 27" iMac/3.4GHz/ICi7/16GB 1333 MHz DDR3 with an additional Thunderbolt display for a two screen set up. Since initial purchase last week, I'm now onto my third replacement TBD and second replacement iMac due to following issue: Set up the first system and noted that the TBD colours were not the same as those displayed on my iMac screen, whites were displayed with a definite blue tinge. I went through all available options to try and get the screens to display the same colours to no avail. Apple promptly swapped out the TBD. Got the second TBD out of the box, hooked it up to the iMac, and lo-and-behold, the exact same problem. I went through all the available options again but with no success. Got in touch with apple support, ran through all the options during a phone call, no success. Spoke to the apple guys boss, sent him a picture of the screens, went through the issues to no avail and he raised it to the apple engineers, still waiting to hear back. In the interim, the apple business manager in the store I bought the system got in touch hoping that my issue had been resolved. On hearing it hadn't they very quickly agreed to swap both iMac and TBD out, which I did today. I've just set the iMac up and hooked up the TBD, and again, colours are not the same. White has a different warmth tone, grey this time rather than blue, still very off-putting working between docs and screens, and offers no confidence working with photos. So, some questions and sense checking: Am I being unreasonable expecting a £3k set-up to display the same colours on both screens? (my old Dell set up did this flawlessly for a fraction of the price) Or should there be no discernible difference as I expect? Is this a known problem? If so, is there a way to fix it? Thanks in advance for any and all feedback.