Apple iMac (Retina 4K, 21.5-inch, 2017) vs Apple iMac (Retina 5K, 27-inch, 2017)

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iMac (Retina 4K, 21.5-inch, 2017) compared with iMac (Retina 5K, 27-inch, 2017)

	AppleiMac (Retina 4K, 21.5-inch, 2017)	AppleiMac (Retina 5K, 27-inch, 2017)
Overview
Released
Released	June 2017	June 2017
Performance
Processor
Processor	Intel Core i5-7400, Intel Core i7-7700 or Intel Core i5-7500	Intel Core i5-7500, Intel Core i5-7600, Intel Core i7-7700K or Intel Core i5-7600K
CPU cores
CPU cores	4	4
CPU threads
CPU threads	4 or 8	4 or 8
Graphics
Graphics	Radeon Pro 555 (2 GB VRAM) or Radeon Pro 560 (4 GB VRAM)	Radeon Pro 570 (4 GB VRAM), Radeon Pro 575 (4 GB VRAM) or Radeon Pro 580 (8 GB VRAM)
Memory
Memory	8 GB, 16 GB or 32 GB	8 GB, 16 GB, 32 GB or 64 GB (better)
Storage
Storage	256 GB to 1 TB	256 GB to 3 TB (better)
CPU
CPU	3.0 GHz quad-core Core i5 with Turbo Boost up to 3.5 GHz, or 3.4 GHz quad-core Core i5 with Turbo Boost up to 3.8 GHz; both configurable to 3.6 GHz quad-core Core i7 with Turbo Boost up to 4.2 GHz	Quad-core Core i5 at 3.4 GHz (Turbo Boost 3.8 GHz), 3.5 GHz (Turbo Boost 4.1 GHz) or 3.8 GHz (Turbo Boost 4.2 GHz); only the upper two bases support the 4.2 GHz Core i7 upgrade with Turbo Boost up to 4.5 GHz
GPU
GPU	Radeon Pro 555 with 2 GB VRAM in the 3.0 GHz base; Radeon Pro 560 with 4 GB VRAM in the 3.4 GHz base	Radeon Pro 570 or 575 with 4 GB VRAM, or Radeon Pro 580 with 8 GB VRAM; graphics are tied to the three base configurations
Memory type
Memory type	2400 MHz DDR4; 8 GB standard, configurable to 16 GB in the lower base or 16/32 GB in the upper base. Two SO-DIMM slots require removal of the glued display and logic board to access (iFixit).	2400 MHz DDR4; 8 GB standard as two 4 GB modules in four user-accessible SO-DIMM slots. Lower base configurable to 16/32 GB; upper two bases to 16/32/64 GB.
Storage type
Storage type	Lower base: 1 TB 5400-rpm hard drive, 1 TB Fusion Drive or 256/512 GB SSD. Upper base: 1 TB Fusion Drive or 256/512 GB/1 TB SSD.	570 base: 1/2 TB Fusion Drive or 256/512 GB/1 TB SSD. 575 base: 1/2/3 TB Fusion Drive or 256/512 GB/1 TB SSD. 580 base: 2/3 TB Fusion Drive or 512 GB/1/2 TB SSD.
Display
Screen size
Screen size	21.5″	27″
Resolution
Resolution	4096 × 2304	5120 × 2880 (better)
Panel
Panel	IPS LCD	IPS LCD
Brightness
Brightness	500 nits	500 nits
Display type
Display type	LED-backlit Retina 4K display; IPS panel confirmed by EveryMac; Apple does not publish native refresh rate in this model’s specification sheet	LED-backlit Retina 5K display; IPS panel confirmed by EveryMac; Apple does not publish native refresh rate in this model’s specification sheet
Display features
Display features	Wide colour (P3); supports one billion colours	Wide colour (P3); supports one billion colours
Connections
Ports
Ports	2 × Thunderbolt 3, 4 × USB-A, SD card slot, Ethernet, headphone jack	2 × Thunderbolt 3, 4 × USB-A, SD card slot, Ethernet, headphone jack
Ethernet
Ethernet	1 Gb/s	1 Gb/s
External displays
External displays	Up to 2	Up to 2
Wi-Fi
Wi-Fi	802.11ac	802.11ac
Bluetooth
Bluetooth	4.2	4.2
Camera
Camera	FaceTime HD	FaceTime HD
Back ports
Back ports	Four USB 3 ports; two Thunderbolt 3 USB-C ports with DisplayPort, Thunderbolt up to 40 Gb/s and USB 3.1 Gen 2 up to 10 Gb/s; SDXC, Gigabit Ethernet and 3.5 mm headphone jack; Kensington lock slot. Thunderbolt 2, HDMI, DVI and VGA require separately sold adapters.	Four USB 3 ports; two Thunderbolt 3 USB-C ports with DisplayPort, Thunderbolt up to 40 Gb/s and USB 3.1 Gen 2 up to 10 Gb/s; SDXC, Gigabit Ethernet and 3.5 mm headphone jack; Kensington lock slot. Thunderbolt 2, HDMI, DVI and VGA require separately sold adapters.
External displays
External displays	Built-in display at full native resolution alongside one 5120 × 2880 display at 60 Hz with one billion colours, two 3840 × 2160 displays at 60 Hz with one billion colours, or two 4096 × 2304 displays at 60 Hz with millions of colours	Built-in display at full native resolution alongside one 5120 × 2880 display at 60 Hz with one billion colours, two 3840 × 2160 displays at 60 Hz with one billion colours, or two 4096 × 2304 displays at 60 Hz with millions of colours
Speakers
Speakers	Stereo speakers; supports Apple iPhone headset with microphone	Stereo speakers; supports Apple iPhone headset with microphone
Microphones
Microphones	Built-in microphone	Built-in microphone
Keyboard and mouse
Keyboard and mouse	Rechargeable Magic Keyboard and Magic Mouse 2; optional Magic Keyboard with Numeric Keypad and Magic Trackpad 2	Rechargeable Magic Keyboard and Magic Mouse 2; optional Magic Keyboard with Numeric Keypad and Magic Trackpad 2
Design and power
Type
Type	All-in-one	All-in-one
Weight
Weight	5.66 kg (better)	9.44 kg
Width × depth × height
Width × depth × height	528 × 175 × 450 mm	650 × 203 × 516 mm
Operating system
Operating system	macOS	macOS
Size and weight detail
Size and weight detail	Dimensions include the stand; weight varies by configuration. A built-in VESA mount version was also available.	Dimensions include the stand; weight varies by configuration. A built-in VESA mount version was also available.
Power supply
Power supply	100–240 V AC, 50–60 Hz, single phase	100–240 V AC, 50–60 Hz, single phase
Materials
Materials	Recyclable aluminium enclosure; arsenic-free glass and mercury-free LED backlight	Recyclable aluminium enclosure; arsenic-free glass and mercury-free LED backlight
In the box
In the box	iMac, Magic Keyboard, Magic Mouse 2, power lead and Lightning to USB cable	iMac, Magic Keyboard, Magic Mouse 2, power lead and Lightning to USB cable