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iMac (Retina 5K, 27-inch, 2020) vs iMac (Retina 5K, 27-inch, 2017)

iMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2

Quick look

Quick look: iMac (Retina 5K, 27-inch, 2020) against iMac (Retina 5K, 27-inch, 2017)
FigureiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Price£1,7993launch price£1,7494launch price
ChipCore i53.1GHz 6-core 10th-generation IntelCore i53.4GHz quad-core Intel
CPU6-coreCPU4-coreCPU
Memory8GBmemory, base8GBmemory, base
Storage256GBstorage, base1TBstorage, base
Display27-inchdisplay27-inchdisplay
Released4 August 20205Available online; Apple gave no in-store day7 June 20176ReleasedIn Apple Stores; orderable online from 5 June 2017.
Security updatesNot available7Security updates15 September 20258Security updates ended
Price
The iMac (Retina 5K, 27-inch, 2020) is £1,799 at launch, per Apple Newsroom (UK); the iMac (Retina 5K, 27-inch, 2017) is £1,749 at launch, per Apple UK Store (archived 23 June 2017).

True to scale

iMac (Retina 5K, 27-inch, 2020) · 650 × 516 mm frontiMac (Retina 5K, 27-inch, 2017) · 650 × 516 mm front

Front faces, from Apple’s published dimensions, drawn to one scale and superposed. Corner rounding is our drawing convention, not a measurement.

Specifications

Each figure is from the source marked by its Mac’s name unless it carries its own small number, which links to where that figure was read.

Body

Body: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, 2017)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Dimensions516 x 650 x 203 mm516 x 650 x 203 mm
Weight8.92 kg9.44 kg
PortsTwo Thunderbolt 3 (USB-C) ports, four USB-A ports, SDXC card slot (UHS-II), Gigabit Ethernet (RJ-45), 3.5 mm headphone jackTwo Thunderbolt 3 (USB-C) ports, four USB 3 ports, SDXC card slot, Gigabit Ethernet (RJ-45), 3.5 mm headphone jack
Thunderbolt ports22
Thunderbolt versionThunderbolt 3Thunderbolt 3
USB-A ports44
HDMINo HDMI port.9No HDMI port.10
SD card slotYesYes
Headphone jackYesYes
KeyboardMagic KeyboardMagic Keyboard
Touch IDNo Touch ID.9No Touch ID.10

Display

Display: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, 2017)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Display size27 in27 in
Resolution5120 x 28805120 x 2880
Display type5K Retina displayRetina 5K display
Brightness500 nits500 nits
Wide colour (P3)YesYes
Nano-texture optionYesNot available11

Chip and memory

Chip and memory: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, 2017)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Chip3.1GHz 6-core 10th-generation Intel Core i53.4GHz quad-core Intel Core i5
Apple siliconIntel processor, not Apple silicon.12Intel processor, not Apple silicon.13
CPU cores64
GraphicsAMD Radeon Pro 5300 with 4GB of GDDR6 memoryRadeon Pro 570 with 4GB of VRAM
Chip options3.1GHz 6-core Intel Core i5, 3.3GHz 6-core Intel Core i5, 3.8GHz 8-core Intel Core i7, or 3.6GHz 10-core Intel Core i93.4GHz quad-core Intel Core i5, 3.5GHz quad-core Intel Core i5, 3.8GHz quad-core Intel Core i5, or 4.2GHz quad-core Intel Core i7
Memory (base)8GB8GB
Memory (maximum)128GB64GB
Memory options8GB, 16GB, 32GB, 64GB or 128GB8GB, 16GB, 32GB or 64GB
Memory upgradeable by userYes, as Apple documents14Yes, as Apple documents14
Storage (base)256GB1TB
Storage (maximum)8TB3TB
Storage options256GB, 512GB, 1TB, 2TB, 4TB or 8TB SSD1TB, 2TB or 3TB Fusion Drive, or 256GB, 512GB, 1TB or 2TB SSD

Connectivity

Connectivity: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, 2017)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Wi-Fi802.11ac Wi-Fi802.11ac Wi-Fi
Bluetooth5.04.2
Ethernet10/100/1000BASE-T Gigabit Ethernet (RJ-45); configurable to 10Gb Ethernet10/100/1000BASE-T Gigabit Ethernet (RJ-45)
External displays (base)22

Camera and audio

Camera and audio: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, 2017)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Camera1080p FaceTime HD cameraFaceTime HD camera
SpeakersStereo speakersStereo speakers
MicrophonesStudio-quality three-mic array with high signal-to-noise ratio and directional beamformingMicrophone

Platform

Platform: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, 2017)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Newest macOSmacOS Tahoe 2615macOS Ventura16
Model identifieriMac20,1 or iMac20,216iMac18,316
Model year20202017

Benchmarks

Benchmarks: Apple iMac (Retina 5K, 27-inch, 2020) against Apple iMac (Retina 5K, 27-inch, 2017)
SpecificationiMac (Retina 5K, 27-inch, 2020)1iMac (Retina 5K, 27-inch, 2017)2
Geekbench 7 (CPU, single-core)1,455171,21017
Geekbench 7 (CPU, multi-core)6,319173,33317

Sources

  1. Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications · Default for iMac (Retina 5K, 27-inch, 2020) · Apple’s figure · read 15 Sep 2026

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  2. Apple Support (UK) — iMac (Retina 5K, 27-inch, 2017) - Technical Specifications · Default for iMac (Retina 5K, 27-inch, 2017) · Apple’s figure · read 15 Sep 2026

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  3. Apple Newsroom (UK) — 27-inch iMac gets a major update · Apple’s figure · read 15 Sep 2026

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  4. Apple UK Store (archived 23 June 2017) — iMac Retina 5K 27-inch, 3.4GHz quad-core Core i5, 8GB, 1TB Fusion Drive, £1,749.00 · third-party figure · read 11 Oct 2026

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  5. Apple Newsroom (UK) — 27-inch iMac gets a major update · Apple’s figure · read 22 Sep 2026

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  6. Apple Newsroom (UK) — iMac receives major update featuring more powerful graphics, faster processors, Thunderbolt 3 and brighter displays · Apple’s figure · read 15 Sep 2026

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  7. Security updates: no end date published. Checked: endoflife.date. Read 22 Sep 2026

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  8. endoflife.date — Apple macOS · third-party figure · read 2 Oct 2026

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  9. iMac (Retina 5K, 27-inch, 2020): No HDMI port. No Touch ID. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications. Read 9 Oct 2026

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  10. iMac (Retina 5K, 27-inch, 2017): No HDMI port. No Touch ID. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2017) - Technical Specifications. Read 9 Oct 2026

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  11. Not published by Apple. Pages checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2017) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — iMac receives major update featuring more powerful graphics, faster processors, Thunderbolt 3 and brighter displays. Read 9 Oct 2026

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  12. iMac (Retina 5K, 27-inch, 2020): Intel processor, not Apple silicon. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications. Read 15 Sep 2026

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  13. iMac (Retina 5K, 27-inch, 2017): Intel processor, not Apple silicon. Checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2017) - Technical Specifications. Read 15 Sep 2026

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  14. Apple Support (UK) — Install memory in an iMac · Apple’s figure · read 18 Oct 2026

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  15. Apple Support (UK) — macOS Tahoe 26 is compatible with these computers · Apple’s figure · read 22 Sep 2026

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  16. Apple Support (UK) — Identify your iMac model · Apple’s figure · read 15 Sep 2026

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  17. Geekbench Browser (Primate Labs) · third-party figure · read 11 Oct 2026

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Not published by Apple

iMac (Retina 5K, 27-inch, 2020). Apple doesn’t publish for this Mac: colours, pixel density, refresh rate, GPU cores, storage upgradeable by user, maximum continuous power, the macOS it shipped with. Geekbench 7 Metal: the Mac chart has no Metal score for this Mac (chart read 10 Oct 2026). Pages checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2020) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — 27-inch iMac gets a major update, read 9 Oct 2026.

iMac (Retina 5K, 27-inch, 2017). Apple doesn’t publish for this Mac: colours, pixel density, refresh rate, GPU cores, storage upgradeable by user, maximum continuous power, the macOS it shipped with. Geekbench 7 Metal: the Mac chart has no Metal score for this Mac (chart read 10 Oct 2026). Pages checked: Apple Support (UK) — iMac (Retina 5K, 27-inch, 2017) - Technical Specifications; Apple Support (UK) — Identify your iMac model; Apple Newsroom (UK) — iMac receives major update featuring more powerful graphics, faster processors, Thunderbolt 3 and brighter displays, read 9 Oct 2026.

If you own one of them

Whether to move is a different question from which is better. Each Mac has a page on it: what its successor changes (the newest Mac in its line where Apple sells one, otherwise the Mac this site treats as its replacement, which can be in another line), what it fetches and whether it still gets updates. Should I upgrade my iMac (Retina 5K, 27-inch, 2020)? · Should I upgrade my iMac (Retina 5K, 27-inch, 2017)?

The pairs a buyer of either Mac would also weigh. Any two Macs in the catalogue can be compared from the chooser.