Hi all, I've recently purchased a Dell U2715H monitor that I'm trying to use with my iMac 27" Mid 2010 and I'm getting a very annoying problem: the monitor starts to lost signal intermittently with its screen going black every few seconds, exactly as this video describes: The monitor seems to work perfectly with a PS4 connected through HDMI, but not with the Mac and its Mini DisplayPort. I've also tried different resolutions and sometimes this seems to minimize the problem, but only for some hours until the screen starts to loss signal intermittently again. It's very annoying and I don't know if it is the fault of OS X El Capitan, of my iMac or its graphics card (ATI Radeon HD 5750) or perhaps a problem caused by the Dell monitor itself, but unfortunatly they don't offer officially support to OS X systems. So, I'm not sure that this monitor is full compatible with all Mac and I'm thinking about returning it. Has someone here tried to use the same monitor with the same iMac model and can post their experience? Thanks!