Hello, I need some advice regarding iMacs in general. I am going to purchase an iMac for the first time and I would like to get some information on graphical aspects/performance. As I was searching Online, I stumbled upon used 5k 27i iMac for £1200 the graphics card was "AMD Radeon R9 M290X 2GB" after that I went to the apple store website and compared the two (spec wise). The apple store iMac has a different graphics card " AMD Radeon R9 M390 with 2GB Vid Memory" - £1600 Can someone give me some advice on: difference between the two graphic cards and which one is much better? I am buying the iMac for gaming (WoW,diablo 3) etc and for programming mainly. thank you in advance!