How do you herd together 14.7 million pixels? You can ask nicely, or you can brandish some heavy-duty hardware. Inside the Retina 5K iMac:

3.5 GHz quad-core Intel Core i5 processor, with Turbo Boost up to 3.9 GHz

8 GB (2x4 GB) of 1600 MHz DDR3 RAM

AMD Radeon R9 M290X graphics processor with 2 GB of GDDR5 video memory

802.11ac Wi-Fi + Bluetooth 4.0

PCIe-based SSD storage and SATA hard drive