What are all the differences between the "Mid-2017" Aluminum iMac models? Which one should I buy?

Please note that all "Mid-2017" iMac models have been discontinued. This Q&A has been updated subsequently and can be quite helpful for anyone considering one of these models whether new or used.

For all practical purposes, there are three different "Mid-2017" Aluminum iMac designs. These consist of the entry-level iMac "Core i5" 2.3 21.5"; the mid-range iMac "Core i5" 3.0 21.5" 4K, "Core i5" 3.4 21.5" 4K, and "Core i7" 3.6 21.5" 4K; and the high-end iMac "Core i5" 3.4 27" 5K, "Core i5" 3.5 27" 5K, "Core i5" 3.8 27" 5K, and "Core i7" 4.2 27" 5K.

With even a quick glance at these iMac models, one could assume that the displays are the primary difference. Although the displays are a notable difference, there are internal differences that perhaps are even more important.

Consequently, an in-depth comparison can be particularly useful to help determine which "Mid-2017" iMac is ideal for your needs.

Photo Credit: Apple, Inc. (Mid-2017 iMac Models)

External Differences

All "Mid-2017" iMac models, regardless of display size, use an all aluminum case design that tapers sharply to a 5 mm edge at the sides of the display. None are VESA compliant, by default, but 21.5" and 27" models both can be configured with a VESA mount option instead of the aluminum stand at the time of purchase for an extra US$40.

The entry-level "Mid-2017" model -- the iMac "Core i5" 2.3 21.5" -- has a comparatively low resolution 21.5" 1920x1080 LED-backlit 16:9 widescreen IPS display. The mid-range "4K" models have a much higher-quality 21.5" 4096x2304 LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 4K" display that runs "pixel doubled" to look like 2048x1152 at twice the density.

Finally, the high-end 27-Inch "5K" models have a 27" 5120x2880 LED-backlit 16:9 widescreen IPS DCI-P3 "Retina 5K" display that looks like 2560x1440 at twice the density.

All of these displays have a fully laminated glass cover and an anti-reflective coating. The "4K" and "5K" displays have a brightness rating of 500 nits.

Each "Mid-2017" iMac also has an integrated 720p "FaceTime HD" webcam embedded in the upper display bezel, speakers integrated at the bottom edge of the display, and dual integrated microphones.

By default, all "Mid-2017" iMac models shipped with a compact aluminum Apple Magic Keyboard and the multi-touch "Magic Mouse 2". For an additional US$30 at the time of system purchase, you could upgrade from the default keyboard to the "Magic Keyboard with Numeric Keypad" and for an additional US$50, you also could upgrade from the Magic Mouse 2 to the "Magic Trackpad 2," which provides multi-touch and pressure-sensitive "Force Touch" capabilities.

Connectivity Differences (or Lack Thereof)

Connectivity is identical for all of the "Mid-2017" iMac models.

All "Mid-2017" iMac models -- regardless of display dimensions or resolution -- have an SDXC-capable SD card slot, four USB 3.0 ports, two Thunderbolt 3 (USB-C) ports, one Gigabit Ethernet port (10/100/1000Base-T), and one 3.5 mm headphone jack.

The "Mid-2017" iMac series also supports 802.11ac Wi-Fi, which is backwards compatible with the slower 802.11a/b/g/n standards, as well as Bluetooth 4.2.

Via Thunderbolt 3, all "Mid-2017" iMac models support one 5120x2880 (5K) external display at 60 Hz with support for one billion colors; two 3840x2160 (4K UHD) external displays at 60 Hz with support for one billion colors; or two 4096x2304 (4K) external displays at 60 Hz with support for millions of colors.

Identification Differences

The "Mid-2017" iMac line shares model numbers with many previous "Tapered Edge" Aluminum iMac models. Specifically, these 21.5-Inch models share model number A1418 and these 27-Inch models share model number A1419.

Consequently, the model numbers are not sufficiently unique for most purposes, like upgrading the RAM or storage, and other identifiers are necessary accordingly.

In software, the Model Identifier is sufficiently unique for just about all purposes. Externally, the EMC number is best as it is less likely to be shared by future models using the same case type, although it is inconveniently located on the underside of the stand.

These identifiers for the "Mid-2017" iMac models are as follows:

Tapered Edge iMac	Subfamily	Model ID	EMC No.
"Core i5" 2.3 21.5"	Mid-2017	iMac18,1	3068
"Core i5" 3.0 21.5"	Mid-2017, 4K	iMac18,2	3069
"Core i5" 3.4 21.5"	Mid-2017, 4K	iMac18,2	3069
"Core i7" 3.6 21.5"	Mid-2017, 4K	iMac18,2	3069
"Core i5" 3.4 27"	Mid-2017, 5K	iMac18,3	3070
"Core i5" 3.5 27"	Mid-2017, 5K	iMac18,3	3070
"Core i5" 3.8 27"	Mid-2017, 5K	iMac18,3	3070
"Core i7" 4.2 27"	Mid-2017, 5K	iMac18,3	3070

Additionally, EveryMac.com's Ultimate Mac Lookup feature also can uniquely identify each of the "Mid-2017" iMac models by their serial numbers.

Internal Differences

The majority of important differences between the "Mid-2017" iMac models are internal.

All "Mid-2017" iMac models use 14 nm "Seventh Generation" Intel "Kaby Lake" processors that are mounted on an industry-standard LGA 1151 socket, but otherwise have substantial differences.

For example, the entry-level "Mid-2017" 21.5-Inch iMac model -- the iMac "Core i5" 2.3 21.5" -- uses slower 2133 MHz PC4-17000 DDR4 RAM and a less powerful Iris Plus Graphics 640 graphics processor that shares memory with the system. The 21.5-Inch "4K" models and 27-Inch "5K" models, on the other hand, use faster 2400 MHz PC4-19200 DDR4 RAM and more powerful Radeon Pro graphics processors with dedicated video memory.

Apple officially reports that the RAM in the 21.5-Inch models is "onboard" and cannot be upgraded, but thankfully this is not true. Instead, memory is installed in two 260-pin SO-DIMM slots. However, accessing these slots is a hassle as it requires one to pry off the display that is glued to the case and remove the logic board. The 27-Inch models, by contrast, have a small "pop off" door on the rear that make accessing the RAM quick and easy. The 27-Inch models have four RAM slots instead of two, also, so they can support twice as much memory as the 21.5-Inch "4K" models and four times as much as the entry-level model.

It is a hassle to upgrade the storage in any of these models, but it also is worth noting that the 27-Inch models, all of which are configured with a hard drive and an SSD merged as a "Fusion" Drive by default, have a SATA III (6 Gb/s) connector for a 2.5" hard drive or SSD as well as a PCIe connector for a small "blade" SSD. If the 21.5-Inch models are not configured with a "Fusion" Drive at the time of purchase, the PCIe connector for the SSD is not onboard and a second drive cannot be installed later.

"Mid-2017" iMac Comparison Chart

The major differences between the entry-level "non-Retina" 21.5-Inch, Retina 4K 21.5-Inch, and Retina 5K 27-Inch "Mid-2017" iMac models -- size, displays, processors, graphics, upgrades and more -- are summarized below:

	21.5"	4K 21.5"	5K 27"
Std. Processor Speeds:	2.3 GHz	3.0, 3.4 GHz*	3.4, 3.5, 3.8 GHz**
Std. Processor Type:	Core i5	Core i5*	Core i5**
Std. Processor Cores:	2	4	4
Turbo Boost:	3.6 GHz	3.5, 3.8 GHz	3.8, 4.1, 4.2 GHz **
Std. Storage:	Hard Drive	Hard Drive Fusion Drive	Fusion Drive
SSD Connector:	No†	No†	Yes
Std. RAM:	8 GB	8 GB	8 GB
Max. RAM:	16 GB	32 GB	64 GB
RAM Upgrade:	Difficult	Difficult	Easy (Door)
Video System:	Iris Plus 640	Radeon Pro 555/560	Radeon Pro 570/575/580
Video Type:	Integrated	Dedicated	Dedicated
Video Memory:	Shared	2, 4 GB	4, 8 GB
Display Size:	21.5-Inch	21.5-Inch	27-Inch
Native Resolution:	1920x1080	4096x2304	5120x2880
Apple Order No (US):	MMQA2LL/A	MNDY2LL/A MNE02LL/A	MNE92LL/A MNEA2LL/A MNED2LL/A
Apple Model ID:	iMac18,1	iMac18,2	iMac18,3
EMC Number:	3068	3069	3070
Original Price (US):	US$1099	US$1299 US$1499	US$1799 US$1999 US$2299
Original Price (CA):	C$1399	C$1729 C$1929	C$2399 C$2649 C$3079
Original Price (UK):	£1049	£1249 £1449	£1749 £1949 £2249
Original Price (AU):	A$1599	A$1899 A$2199	A$2699 A$2999 A$3449

* By custom configuration, the iMac "Core i5" 3.0 21.5" 4K and "Core i5" 3.4 21.5" 4K could be custom configured with a 3.6 GHz Quad Core "Core i7" processor (I7-7700) for an extra US$300 at the time of initial system purchase. EveryMac.com also has documented this custom configuration as its own model.

** The iMac "Core i5" 3.5 27" 5K and "Core i5" 3.8 27" 5K additionally could be custom configured with a 4.2 GHz Quad Core "Core i7" processor (I7-7700K) for an extra US$300 or US$200, respectively. EveryMac.com also has documented this custom configuration as its own model.

† If the 21.5-Inch models were not configured with a "Fusion" Drive at the time of purchase, the PCIe connector for the SSD is not onboard and a second drive cannot be installed later. If they were configured with a "Fusion" Drive, this connector is onboard and occupied by the SSD.

So, which one should I buy?

Just compared to one another, and ignoring subsequent models, choosing between the "Mid-2017" iMac models is more difficult than it was for the "Late 2015" models before them, at least if upgrades are important to you. It is possible to upgrade both the 21.5-Inch and 27-Inch "Mid-2017" iMac models, it is just easier to upgrade the 27-Inch models.

If price is your primary concern, the entry-level iMac "Core i5" 2.3 21.5" was cheapest when new, although values may have shifted somewhat on the used market. It has a significantly inferior display to the 4K models, though, as well as a lower 16 GB memory maximum and a pathetically slow 5400 RPM hard drive by default. However, it is possible to upgrade the hard drive later and it still holds its own in terms of performance with the next level up for many single core tasks.

Among the 21.5" 4K models, EveryMac.com would suggest that the iMac "Core i5" 3.4 21.5" 4K originally represented a better value than the iMac "Core i5" 3.0 21.5" 4K because the extra US$200 got you a faster processor, better graphics processor, and a "Fusion" drive, which provides both a hard drive and an SSD and opens the door to additional storage upgrade possibilities down the road, as well. These models can be equipped with a respectable maximum of 32 GB of RAM, too.

If your budget allows it, the 27-Inch "5K" models are better systems with an incredibly large and beautiful display, easy-to-upgrade RAM, and fast graphics processors.

All three default 27" configurations are good choices on the used market, but the least expensive option, the iMac "Core i5" 3.4 27" 5K, or the high-end default option, the iMac "Core i5" 3.8 27" 5K, are likely to make the most sense for the majority of users. The middle option, the iMac "Core i5" 3.5 27" 5K, has a processor and graphics processor that are only slightly faster than the entry-level model, whereas the high-end default option has a significantly faster processor, much faster graphics processor (with 8 GB of VRAM), and twice the storage with a much larger SSD (128 GB), which results in much faster disk performance overall.

Of course, if price is no object, the custom-configured iMac "Core i7" 4.2 27" 5K definitely was worth considering. Although the value on the used market may vary a bit, when it was new, it represented a good value, even, as it cost 9% more and is 9% faster in single core tasks and 26% faster in multicore tasks compared to the high-end default iMac "Core i5" 3.8 27" 5K.

Please also see EveryMac.com's Ultimate Mac Comparison feature to dynamically compare any iMac model to any other Mac.

New & Used iMac Purchase Options

There are many places to purchase a used "Mid-2017" iMac. However, buying from a quality merchant with an extensive track record in the Mac market will provide the best experience and save you money and time, too.

In the US, site sponsor Adorama sells new iMac models with free shipping. Other World Computing sells used and refurb iMac models at bargain prices with free shipping, as well. Finally, if you need to sell an iMac, A+ BBB-rated Cash for Your Mac will buy your older iMac with an instant quote and prompt payment.

In the UK, site sponsor Hoxton Macs sells used iMac models with a one-year warranty and free next day delivery throughout the UK. Delivery across Europe also is available starting at just £9.99 for two-day delivery to France and Germany.