I have had my 27" 5K 3TB FUSION DRIVE 32GIG RAM replaced by apple. Why? Well several times I would shut down my computer I would have horizontal lines flash across horizontally the screen, colors where orange, black, white, red and it was usually just two colours, and one time it was green and white lines. This I would tolerate happening to my mac. I expect my iMac to be in a healthy condition and not break down with gentle care. I took it to Apple Store and they tested it and found the device was unhealthy so they swapped out the Logic board. I went in to get, and the same tech that tested it when I brought it in, was saying he reluctantly wanted to give it back to me. I took it home. Then a day or so goes by, more lines of color. I didn't do anything about it at first, then it occurred again a couple days later. This was Damn disturbing. I brought it in again to Apple, they kept it, and to make this long story short, they swapped out the logic board four more times, and I was going insane. I kept calling into apple to check on my loved iMac. So I kept insisting that it should be a quality product for close to 5 grand machine and its failing on the early of third year of ownership. I requested that the computer be replaced with a replacement. Well, I kept insisting, and defending consumer rights in logical sense, and Apple came through, they sent the return postage to the Fulfillment Dept. so I could send in my crap computer and then they sent me a brand new late 2015 Built to Order iMac 5K 32GigRam 3TB Fusion Drive, and I am happy with Apple and all the support I received, but let me tell you, it was a ****ing stressful time, my iMac is working fine so far, and I am pleased overly with Apple and their products and handling of sticky situations.
