I've been using a 27" iMac, 2011 Quad-Core, i7, 32GB RAM,2TB SSD,Last DVD/CD Drive Model, Refurbished for Apple in 2013. Although I have been happy with the overall speed, I had graphics Card issues, and haven't been able to upgrade past El Capitan, sometimes not being able to even open popular webpages. Apple has hung us out to Dryad we still don't know if Apple is going to bring the 27" 5K iMac back, and I don't want Separates, preferring the 5K Nano-Textured 27" 5K Screen, instead of the 24" M-Series iMac. I just Jumped off the Cliff, and bought a 5K, Nano-Texture Screen, 16GB XT Graphics card, 8 TB SSD,Upgradeable RAM, 3.6 Ghz i9, 10-Core Intel Processor, and I Love it! The Screen is Accurate, Low-Glare and Superb, the Speed is awesome, and for 3 years I'll have Apple Care Plus, so I no longer have to worry about what Apple is going to do, and i won't be forced to buy what I don't want. I have been patient, Apple disregarded the Graphics-Issues on it's former Top-of-the-Line 17" Mac Book Pros, 27" iMacs with Retina Displays, and now won't even tell its Customers if the iMac 27" its even going to be replaced. i solved My Own problem, and if I wasn't loyal, I would have jumped to another Computer maker.