I'm purchasing a new 27" iMac and am putting a tb ssd and i7 processor in it. I will also be maxing out the RAM. My questions is do I need to upgrade the video card too? I will never game on this machine, but will use it to edit pictures in Photos and edit some 4k video in iMovie that I take with my 6s+. I would rather put the $250 towards Apple Care and Ram, but want to make sure that I'm not missing out on something. Please Help!