I recently upgraded my 2009 Mac mini to a (secondhand) 2014 Mac mini. I've used the 2009 as a media computer for years, firstly plugged into a 24" monitor, and then into a 40" Sony Bravia TV. I never had any problems with the display, but I am having problems with it on the new 2014 mini. The screen goes all purple and green when plugged in via HDMI either from Mini DisplayPort or from HDMI to HDMI. I bought a Mini DP to VGA adapter to try that, and the colour is fine but the resolution sucks. It either leaves black bars on the side of my TV, cuts off the top and bottom, or stretches. The TV is a Sony Bravia, which is on the older side (10 years?) but is still full HD with HDMI ports. The colour is fine when viewed via screen sharing from another Mac. I have tried changing the colour profiles, etc. in System Preferences but it just makes it slightly different shades of purple and green. The colour is fine at 720p but the resolution looks awful. I ran my old Mac mini just fine at 1360x768, which is what I'm trying to run this at. I've seen other people have had the same issue upon Googling but haven't found a resolution. Is there anything I can do to solve this short of spending £400 on a new TV? The Mac mini is running Yosemite. Should I upgrade it to El Capitan? Edit: Added picture.