There are tons of reasons why you might need to reformat your Mac: It’s slowing down, filling up with too many unneeded files to delete manually or suffering from major technical issues that can’t be fixed otherwise.
Or maybe you’re just selling it as you move on to a better, faster Mac and need to remove everything.
Yesterday, Amazon announced that they would begin streaming Amazon Prime movies in 4K Ultra HD, free of charge. This follows an announcement by Netflix in March that they would allow subscribers to stream 4K shows in Ultra HD for a small additional charge every month.
Of course, neither the iPhone, iPad, or the Apple TV support 4K video… but the new iMacs with Retina Display do. Yet despite this, Netflix and Amazon don’t actually stream 4K video to the Retina iMac. The best you can get is plain old 1080p.