Apple leapt straight to 5K to make the 27-inch Retina 5K iMac the desktop computer to own. In May 2015, Apple reduced the top model’s price by £150; it has a 3.5GHz quad-core Intel Core i5 (there’s a 4.0GHz Core i7 option), a 1TB Fusion Drive, 8GB of RAM and an AMD Radeon R9 M290X with 2GB video memory. At the same time Apple updated the mid-range 27-inch with a Retina 5K display and new graphics processor. Other models are unchanged, with one non-Retina 27-inch and three 21.5-inch models. All except the entrylevel iMac have a quad-core processor.