Apple iMac review (21.5-inch, 2015): 4K is optional, faster hard drives shouldn't be

You'll want to upgrade to a Fusion Drive to get the best performance.

No, it's not just a CPU refresh. Apple started selling a new line of iMacs today, and yes, while they have fresh processors and graphics cards inside, that's really the least of it. Going forward, all the 27-inch models have a 5K screen -- not just the flagship we reviewed last year -- while the 21.5-inch version now has an optional 4K panel. Across the board, too, these new 4K and 5K displays have a wider color gamut, although the difference is fairly subtle. Possibly more important than the iMac itself, though, are the input devices: Apple redesigned the wireless keyboard, mouse and trackpad, adding rechargeable batteries and, in the case of the touchpad, pressure-sensitive Force Touch gestures.

I've been spending a few days with the new iMac, and chose to review the 4K 21.5-inch edition in particular since this is the first "small" iMac with a Retina display. Between the crisper screen, compact footprint and a lower price than the 27-inch models, it has the potential to hit the sweet spot for a lot of people. Just be sure to upgrade the hard drive before you place your order.


I felt a little nervous at first, using this unannounced computer out in the open at my office desk. What if someone walked by, uploaded a spy shot to Twitter and blew my cover? What if someone at our sister site TechCrunch saw? The truth is, it was the new keyboard and trackpad that I had to hide; the Mac itself has the same design as ever. Same dimensions. Same unibody aluminum enclosure. Same metal stand with a pass-through for the power cable. The bezels still measure 5mm thick, and are still pretty to look at from the side, although they don't have any bearing on the overall footprint.

To that end, the iMac still puffs out in the back to accommodate all the circuitry inside. The ports are the same except the two Thunderbolt sockets have been replaced with Thunderbolt 2 connections, which have the same shape and labeling. Finally, the speakers are still hidden under the lower bezel, and they're still loud.

Truly, the only potentially visible change is the color gamut, but I'm pretty sure anyone with discerning enough eyes to immediately tell the difference is working at Pixar, not Engadget.


Now that I've flown through all the same-y stuff, let's focus on one of the few things that has changed: the screen. Although the 21.5-inch iMac used to max out at 1,920 x 1,080 resolution, you can now get it with an optional 4K (4,096 x 2,304) Retina display. Meanwhile, on the 27-inch version, 5K resolution (5,120 x 2,880) is now the standard, whereas before it was originally reserved for a flagship $2,499 configuration (with lower-end models later offered starting at $1,999).

Either way, Apple says the screen density is now the same on the 4K 21.5-inch iMac as it is on the 27-inch 5K version. Previously, the lower-end 27-inch iMacs had 2,560 x 1,440 resolution, which means the pixel count is now quadrupled. In the case of the 21.5-inch version I reviewed, the difference is more dramatic: Those 9.4 million pixels amount to more than 4.5 times the resolution of the previous generation. And for a certain kind of shopper, that will come as a relief. Maybe you don't have enough room on your desk to comfortably use the bigger 27-inch version, but still want the sharpest-possible display. If that's you, you'll happily pay a $400 premium to get the 4K iMac over the entry-level Full HD one. (I'd say the iMac could also make for a lovely secondary display, but alas, you still can't use it as a monitor for your laptop or Mac Mini.)

Regardless of the size, both the 4K and 5K screens extend beyond the sRGB color gamut in the previous generation to the wider P3 range. It offers 25 percent more available colors, according to Apple, particularly in the red and green areas of the spectrum. Blues are about the same versus sRGB, but you'll still theoretically notice a difference in cases where blues are combined with either reds or greens (say, purples and shades like cyan). To make this happen, Apple moved from white LEDs to red-green phosphor LEDs that can capture more red and green light to appear onscreen. Apple says it already covered 100 percent of sRGB in older iMacs, and moved to P3 because many of its customers are already using DSLRs and pro video cameras capable of capturing colors that aren't always recognized in the sRGB spectrum.

As you all know, I don't represent that target market: I'm neither a photography nor a video enthusiast, and my job as an Engadget editor doesn't require me to have a discerning eye for color. So it shouldn't come as much of a surprise that the benefits of P3 are somewhat lost on me. I had the opportunity to view some "before and after" photos with colors representing what you'd see on the old sRGB panel and the new P3 one, and the differences were generally subtle; colors look slightly punchier than they would have otherwise. There's also slightly better detail preservation, particularly in shadowy parts of the image. What I'm about to say isn't a technically correct explanation, but it almost looks as if someone bumped up the saturation, or as if the images were taken in HDR mode. Again, that's not actually what's going on behind the scenes, but it's the best way I can explain the difference here -- especially to shoppers who might not get to see the same comparison images that I did.

The funny thing is that while I might not have noticed the richer colors on my own, now that someone has pointed them out, they're hard to un-see. Things that I see every day -- dock icons, an orange label in Google Calendar, the red font I use to highlight important things in emails to my team -- look different. Not just brighter, but truer; more pristine. Reds are closer to true reds. Oranges are more orange. You get the idea.

Unfortunately, there's little else I can do to help illustrate the difference, since chances are you're using an older sRGB screen yourself, if that. My best recommendation, then, is to head over to an Apple Store if possible and take a look at the screen in person. Perhaps you'll even get to see one of the new P3-grade iMacs displayed next to an entry-level sRGB one, but no promises there. Barring that, you're just going to have to trust me when I say that the P3 panel is indeed more color-rich, and that the difference can also be tough to spot unless you know what to look for.

Keyboard, mouse and trackpad

If the iMac's new color gamut and CPU choices seem like modest changes, it's the bundled input devices that make this a more substantial update than it may initially seem. All of the iMac's matching peripherals -- the wireless keyboard, mouse and trackpad -- now recharge through a Lightning port. Yep, that's right, gone are the AAs, and so is the battery barrel that housed them.

In all, you should expect to get a month's use out of each device before you have to recharge. In the case of the mouse, the Lightning port's location on the bottom side means you can't use it while it's rejuicing. But, because the keyboard's and trackpad's charging ports are each tucked away on a back edge, you can indeed use them while they charge. Accordingly, the new peripherals come with a Lightning cable in the box. As before, too, they ship pre-paired with your system, but if you're using them with an older machine, they'll automatically pair when you connect to the iMac via a Lightning cable for the first time. In fact, I had to do this with the Trackpad, which came in a separate box, as if I had bought it separately.

Speaking of the sort, the keyboard and mouse come in the box by default, with the Trackpad offered as an upgrade option on the configure-to-order page. If you're the owner of an older iMac and want to swap in the new peripherals, they cost $99 for the keyboard, $79 for the mouse and $129 for the trackpad.


Without that battery compartment, too, Apple was able to make each of these devices lighter and, in the case of the trackpad and keyboard, thinner as well. Because the keyboard is now missing that cylindrical battery barrel, it has a slimmer design and lies at a flatter angle. I found it comfortable to type on, although I don't recall having any complaints about the previous design, and unfortunately I don't have an older keyboard lying around that I can use for comparison purposes.

Additionally, the keyboard's footprint is 13 percent smaller than before, yet despite that the individual buttons are actually larger now, with the Function row in particular reaching the same vertical height as all the other buttons. You'll also find the key spacing is more in line with what we saw on the 12-inch MacBook. Lastly, Apple says it reengineered each of the keys, adopting a refined "scissor" mechanism to help the buttons move up and down in an even, reliable way. All told, Apple is promising 33 percent better key stability, which is to say even if your finger strikes the corner of the key instead of the center, it'll be that much more likely to register as a "normal" press.

For my part, I was always able to hit the button I meant to, even without looking. I generally made few typos, too, though occasionally a key would still fail to register my press -- a problem I've noticed on flat, shallow keyboards in general. Perhaps in a future update, Apple will adopt the same underlying keyboard mechanism in use on the 12-inch MacBook.

Magic Mouse 2

Like the iMac itself, the new Magic Mouse is difficult to tell from its predecessor, at least at a quick glance. As before, the mouse has a glassy white surface that responds not just to button presses, but also to multitouch gestures, similar to what you'd otherwise do on a trackpad. Look closer, though, and you'll see that while the Magic Mouse 2 is as thick as before, it's noticeably lighter, thanks to the lack of AA batteries inside. Apple also redesigned the feet on the bottom for smoother gliding. As I said about the keyboard's flatter angle, the new foot design here works, but I also had no complaints about the glide factor on the previous model; the old version also worked well on a variety of surfaces.

If anything, the rechargeable battery is a bigger deal than the new feet. In particular, the mouse has a quick-charging feature that allows it to regain nine hours of use after just two minutes of charging. That's important, since the mouse can't be used while it's charging, the way the keyboard can.

Ultimately, whether you choose the mouse or trackpad boils down to personal preference. Personally, I've always been a mouse person: Mice are comfortable to rest my hand on, and I enjoy the tactile feedback of pressing a button (as I've argued before, Apple's pressure-sensitive Force Touch trackpads don't quite feel like the real thing). That said, the button on the Magic Mouse is a little noisy; if that annoys you, using the Magic Trackpad with tap-to-click enabled could be a good alternative.

Magic Trackpad 2

As I hinted earlier, I'm not a huge fan of the Force Touch trackpads on MacBooks; I miss the tactile feel of being able to press a button on the old touchpad. But, I enjoy Force Touch a good deal more on the new Magic Trackpad. I'm going to chalk that up to ergonomics: According to Apple, the underlying technology here is the same as on the MacBook, which means there's nothing different going on under the hood. In case you need a refresher, there are four pressure-sensitive force sensors plus a so-called Taptic Engine that uses vibrating feedback to simulate the feeling of a button press (neither the Magic Trackpad nor MacBook touchpad really have a button; both feel like stiff pieces of glass when powered off). As on the MacBook, you can use a long-press, or "Force touch," to do everything from peek at files in Finder to quickly fast-forward movies in iTunes.

For people who already own one of the new Force Touch-enabled MacBooks (or even a Force Touch gadget like the Apple Watch or iPhone 6s with its 3D Touch screen), these gestures and tricks will all seem familiar. If you found them useful before, that may well convince you to use the Magic Trackpad instead of the mouse. If, like me, you think Force Touch is a little gimmicky in OS X, it comes down more to ergonomics.

Indeed, that's why the trackpad has enormous appeal for me. The second-gen Magic Trackpad has 29 percent more surface area than the original, and you obviously get way more space than you would on a Magic Mouse or MacBook touchpad. I find the increase in surface area alone makes Force Touch easier to use here than on a laptop. Also, when the pad is placed farther away from the keyboard (as opposed to right below it), that has an effect on where I rest my hand, and it puts my wrist in a more natural position. Between that and the quieter "button" feedback I'd otherwise get on the Magic Mouse, I ended up getting a lot of use out of the trackpad -- even if I'm otherwise indifferent to Force Touch.


Geekbench (multi-core)


Blackmagic (average read/write speeds)

iMac (2015, 21.5-inch, 3.1GHz quad-core Core i5 processor, 8GB RAM, Iris Pro 6200 Graphics)

11,331 (32-bit) / 12,679 (64-bit)


95.2/93.2 MB/s

iMac with Retina display (2014, 27-inch, 3.5GHz Core i5, 8GB RAM, 2GB AMD Radeon R9 M290X)

11,344 (32-bit) / 12,394 (64-bit)


659.0/311.5 MB/s

Mac Pro (2013, 3.7GHz Intel Xeon E5-1620, 16GB RAM, dual 2GB AMD FirePro D300 GPUs)

12,650 (32-bit) / 14,207 (64-bit)


918.6/761.2 MB/s

iMac (2013, 27-inch, 3.4GHz Core i5, 8GB RAM, 2GB NVIDIA GeForce GTX 775M)

10,920 (32-bit) / 11,867 (64-bit)


667.9/318.1 MB/s

iMac (2012, 27-inch, 3.4GHz Core i7, 8GB RAM, 2GB NVIDIA GeForce GTX 680MX)

13,045 (32-bit)


409.6/320.1 MB/s

iMac (2012, 21.5-inch, 3.1GHz Core i7, 16GB RAM, 512MB NVIDIA GeForce GT 650M)

12,577 (32-bit)


409.6/320.1 MB/s

While the 27-inch models received an upgrade to Intel's new sixth-gen Core processors and fresh AMD R9 M300-series graphics, the 21.5-inch version runs fifth-gen CPUs with up to Intel Iris Pro 6200 graphics. This would make sense, since Intel doesn't yet seem to have any sixth-gen desktop chips that work with Iris Pro; as of this writing, the list is limited to five fifth-gen processors, all of which were released not long before the refreshed iMac came out. (Which is to say, these processors aren't exactly old, per se.) What's vexing is that until today, Apple was in fact selling the 21.5-inch model with an optional NVIDIA graphics card, so this would seem to represent a change of heart. Aside from trying to keep the smaller model affordable for casual users, I imagine the company is trying to incentivize folks to pay more for the bigger version -- and it's betting power users will be willing to do just that. That's a shame, because a 4K display is probably at its best with a dedicated GPU.

The unit I've been testing is one of the higher-end 21.5-inch configurations, one with a 4K screen, 3.1GHz quad-core Core i5-5675R processor, 8GB of 1,867MHz DDR3 RAM and Intel Iris Pro 6200 graphics. Performance was fine for web browsing and light multitasking, with benchmark scores that matched the flagship 5K iMac I tested last year. The 802.11ac wireless radio also delivered fast speeds, although I admittedly spent most of my time with an Ethernet cable plugged in the back. I did unfortunately encounter the occasional bout of sluggishness. One time, for instance, Spotlight search paused before displaying results, leaving some artifacting on the screen. I also sometimes found that if I tried to do something immediately after boot-up -- say, open a file in Finder -- I'd be met with a short delay. In moments like this, I felt as if I hadn't fully regained control of the system, even though the desktop appeared to have loaded. Thankfully, at least, hiccups like these were the exception, not the rule.

If you're not careful, you also might end up with frustrating disk speeds. Even on my review unit, which would cost $1,499 at retail, I have just a traditional hard drive, one that spins at a modest 5,400 revolutions per minute. (Seriously, what year is this?) I routinely waited through a lengthy startup of around 47 seconds, with the machine taking seven seconds just to show the splash screen. In contrast, an iMac with a Fusion Drive that I tested last year (and the year before that), booted up in just 15 seconds or so. What's more, in the Blackmagic Disk Speed Test, the new iMac rarely broke 100 megabytes per second on either read or write speeds, not even when I simulated the lightest-possible workload. That would be fine for basic use, like email and Facebook, but people who intend to use their 4K iMac to do things like edit 4K video shot on their new iPhone 6s might be disappointed.

From Apple's perspective, the company is doing shoppers a favor by offering Fusion Drives on more configurations, and charging less for an up-sell. Specifically, the company is now offering them standard in models starting at $1,999, and upgrading to one on the configure-to-order page now costs $100, down from a range of $200 to $250 in the last generation. This is a step in the right direction, and I get that Apple wants to keep the iMac's starting price down to lure in more budget-conscious shoppers, but at least make Fusion Drives standard on some of the more expensive configurations, like the $1,499 sku I tested. To me, this feels like the "16GB iPhone" debate, redux: 5,400 rpm hard drives are about as passé as 16GB of storage is on flagship phones, and in both cases, the rest of the industry has moved on.

Configuration options

Both the 21.5- and 27-inch iMacs have the same starting prices as before, with the smaller model going for $1,099 and up and the bigger one priced from $1,799. Starting with the 21.5-inch size I reviewed, the base-level specs include a dual-core 1.6GHz Core i5 processor, a 1,920 x 1,080 display and integrated Intel HD 6000 graphics. The next model up, a $1,299 configuration, steps up to a 2.8GHz quad-core Core i5 processor and Intel Iris Pro 6200 graphics. Finally, there's the high-end unit I tested, which for $1,499 brings a 3.1GHz quad-core Core i5 processor, that 4K Retina display with the expanded color range and the same Iris Pro 6200 graphics as on the model just below it. Regardless, each of these comes standard with 8GB of RAM and a 1TB, 5,400 rpm hard drive.

From there, you have some configuration options. You can double the RAM to 16GB regardless of the model you buy. There's also a quad-core Core i7 CPU available, but it's only offered as an upgrade option on the top-end $1,499 edition. Throughout, too, you can swap in different storage solutions, although your options get more plentiful as you step up to the $1,499 configuration. For instance, on the $1,099 model you only have the choice of upgrading to a 1TB Fusion Drive or a 256GB SSD. With the $1,299 version, your choices include a 2TB Fusion Drive and either 256GB or 512GB of solid-state storage. It's only on the $1,499 configuration that you can choose any of the above.

While I have you here, let's go over what you get on the 27-inch version -- after all, many of you will want the same color range as on the unit I reviewed, just with more screen real estate and stronger performance. As I said, the larger iMac starts at $1,799, a price that includes a 3.2GHz quad-core Core i5 processor, a 2GB AMD R9 M380 GPU and a 1TB hard drive spinning at 7,200 rpm. If you step up to the $1,999 model, you get the same CPU, but a slightly faster GPU (a 2GB R9 M390) and a 1TB Fusion Drive instead of a traditional HDD. Finally, the highest-end $2,299 model has a slightly faster 3.3GHz quad-core Core i5 processor, AMD R9 M395 graphics with 2GB of video memory and a 2TB Fusion Drive. Across the board, you get a 5K (5,120 x 2,880) display with the expanded P3 color range and 8GB of memory.

Real quick, the 27-inch iMac has some up-sell options of its own. The two higher-end configs can be had with a 4.0GHz quad-core Core i7 processor, while a 4GB AMD R9 M395X GPU is offered on all three models. More RAM -- 16GB or 32GB -- is also an option across the board. You will find that storage options vary somewhat: the entry-level $1,799 model can be had with a 1TB, 2TB or 3TB Fusion Drive or a 256GB or 512GB SSD, while the two higher-end configurations add a 1TB SSD option. (You can't upgrade to a 1TB Fusion Drive on the two more expensive models; just 2TB and 3TB.)

The competition

The upgraded iMac doesn't have much competition, especially for the smaller 21.5-inch model. If you're OS-agnostic enough to consider a Windows machine, I'd normally point you toward Dell's premium XPS line. The problem, though, is that as of this writing, the XPS 27 listed on Dell's site runs fourth-generation Core processors, compared with sixth-gen in the refreshed 27-inch iMac. Meanwhile, Dell's XPS 18 is actually a battery-powered, portable all-in-one, putting it in a different category altogether than the iMac. If you're in the market for a 27-inch machine, the XPS 27 has a Quad HD screen, and starts at a more reasonable $1,700, but I suggest waiting for Dell to refresh the internals. It's a similar story with Lenovo: The 23.8-inch A540 and 27-inch A740 listed on the company's site could in theory make decent alternatives, but as of this writing they're being sold with fourth-gen Intel CPUs.

If anything, your best alternative might come from HP. The company just last week unveiled a pair of refreshed Envy-series all-in-ones, with 23.8- and 27-inch Technicolor-certified screens, optional 4K resolution and sixth-gen Core processors. Like the iMacs, too, they support up to 16GB of RAM and your choice of an SSD, HDD or hybrid disk. They're not on sale yet, but they will be soon: Look for them on November 1st, starting at $1,000 for the Envy 24 and $1,200 for the 27.


The iMac is still the best all-in-one, with an attractive (if predictable) design, near-standard 4K and 5K screens, and even better color accuracy than before. The 21.5-inch version is in some ways the more interesting of the two models, as this is the first time the smaller Mac has been offered with a Retina display. That's good news for people who are willing to pay a premium for a sharper screen, but don't quite have the desk space for the bigger 27-inch model. In addition to the computer itself, the peripherals come close to stealing the show: They're finally rechargeable, for one, and the keyboard in particular takes up less space, despite having larger buttons. The Magic Trackpad now supports Force Touch too, so if you happen to enjoy those pressure-sensitive gestures on the MacBook Pro, Apple Watch or iPhone 6s, you can now have the same experience here.

As you can see, then, the iMac mostly hits the right notes, although I wish Apple were more generous with the other specs -- besides display quality and resolution, that is. The 21.5-inch version is no longer offered with discrete graphics, not even on the 4K edition, which seems like a mistake. Meanwhile, hybrid Fusion drives only come standard on machines priced from $1,999. Again, I love the improved screen, but having faster storage for the money and the option of more robust graphics would have improved my boot time and maybe eliminated the few hiccups I experienced. It's great that more iMacs now have 4K and 5K panels, but until Apple redesigns the hardware, which has looked the same for several years now, the best thing the company can do is double-down on performance.