I have a U2415 which I calibrated using the custom color preset, but I noticed that the colors change slightly whenever the input mode is switched or an exclusive full screen application such as a game is launched (I'm assuming the input source in this instance is simply being set to whatever it already was, but the result is still the same).
An easy test I tried is simply alt tabbing a full screen game and seeing different colors on the desktop.
Changing the input source via the OSD to something else and back works as well.
The new colors are always slightly warmer, and in order to get my previous calibration I have to change the preset mode to something else (standard, for instance) and back again, or turn the monitor off and on. This seems to temporarily resolve the issue, but it's a major inconvenience to do every single time.
Please note that the actual custom color values remain the same throughout.
I tried to use both MDP and DP cables, tried different ports on my GPU, even tried the monitor on an entirely different PC, but nothing seems to fix this bizarre problem.
I really hope you can help me. Please let me know if you require any additional information.
Apologies for missing your post. You didn't install the DDM (Dell Display Manager) did you? Its presets under Auto Mode (18 choices) are different per application and can do what you are describing. For testing, if you did install DDM, uninstall it, then restart the computer and retest.
Here it is.
The video starts after I alt-tabbed from a game. What you see is me quickly switching from the erroneous 'custom color' to color temp and back to the way custom color should be.
You can manually jump from the beginning to the end to see the difference.
I still have doubt that the monitor is at fault here. Since still inside the 3 year warranty period, you may initiate a monitor exchange. Test the replacement before sending any monitor back to Dell. If the replacement monitor does not have the issue, keep it and send us the original monitor. If the replacement monitor has the same issue, I doubt that they both could be defective. Send the replacement monitor back to Dell. Look to the cabling, video card drivers, or video card as the culprit.
* For exchange instructions, go back to the top of this monitor Forum
* Open the announcement, "FAQ Monitor"
* Read through, "Monitor warranties and replacement instructions"