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by Jason Snell & Dan Moren

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By Jason Snell

Review: 27-inch iMac with Retina 5K Display

When it was first announced in 1998, and for most of the years that followed, the name iMac represented Apple’s affordable all-in-one “computer for the rest of us.” The iMac was never the kind of Mac a self-respecting Apple nerd would use—for them there were Power Macs and Macs Pro, PowerBooks and MacBooks Pro.

But over the last few years, Apple has been slowly pushing its other Mac desktop models into corners. You can’t buy a Mac Pro for less than $3,000, and after ignoring the Mac mini for two years, the latest update drops support for quad-core processors, making it more of a low-end model than ever before.

And now here comes the clincher: A new top-of-the-line 27-inch iMac that’s not just fast, but sports a gorgeous Retina display that brings nearly 15 million pixels to the party. It’s enough to make people who fully expected to buy a Mac mini or Mac Pro switch sides and pledge allegiance to iMac Nation. People like me, for one.

It’s all about the screen

Look, the reason you’ll buy the 27-inch iMac with Retina 5K Display (hereinafter, “Retina iMac”) is because of the screen. Yes, many of its other specs are better than the rest of the iMac line, last updated in June. But the attraction here is the crazy screen, a 27-inch display with four times the pixels of the 27-inch standard iMac.

This is a legitimately gorgeous screen, one powered by a panoply of display technologies. A timing controller that combines two streams of DisplayPort 1.2 on a single chip. Oxide TFT technology to help brightness uniformity and refresh rates. Organic passivation tech from the retina iPad line in order to reduce cross-talk between pixels. Power-saving LED backlighting to reduce power consumption. A photo alignment process to improve on-axis contrast, and a compensation film for off-axis contrast.

If the buzzwords don’t do it for you, then let me say again: It’s beautiful. If you’ve been through the Retina transition on the iPad or iPhone, you know how much nicer a screen is when you can’t see the pixels at all. While the Retina iMac (like the Retina MacBook Pro before it) doesn’t offer quite as high a pixel density as iOS devices, neither do you hold either of these devices in your hand and up to your face at close range. In the end, Apple’s definition of Retina—that from a normal distance you can’t see the dots—definitely applies.

If you’ve seen the Retina MacBook Pro, you’ve seen what the Mac interface looks like when four pixels are doing the work that only one used to do. Everything’s sharper. Photos look real, like they were printed on paper. Text is razor sharp. Even the Dock is more pleasant, because the icons that inhabit it are subtly detailed in ways they weren’t before.

Retina Screen Comparison
A close-up photo composite of Bryan Bell’s BBEdit icon on the Retina 5K iMac (left) and a non-retina display.

It looks good, but feels subtle—until you turn back to a non-Retina Mac display and are confronted with the brutal reality of a low-DPI screen. “How did we live like this?,” you’ll cry out to no one. Is a Retina display absolutely necessary in life? There are very few people who need this many pixels—designers and photographers come to mind. But, then, you could argue that about high-resolution displays on any device: We got along fine without them, and they’re not necessary, but life is sure nicer now that we’ve got them.

While the Retina MacBook Pro will give you a good idea what the Mac interface looks like on a Retina display, there is one fact to keep in mind: The iMac’s got more than three times the pixels of the 15-inch MacBook Pro.

While recent iMacs have been able to double as an external display via something called Target Display Mode, the Retina iMac can’t. This is cutting edge technology, and pumping this volume of pixels through a display cable or series of cables is a serious challenge. With the Retina iMac, Apple has punted: There’s no better way to attach a computer to a display like this than to build them together. In the future, there will undoubtedly be standalone 5K displays—even from Apple!—and ways to connect them to other Macs effectively. For now, though, the Retina iMac is an island, its own display and computer as one.

Bottom line: This is a gloriously bright high-resolution display that looks good from pretty much any angle.

It’s still an iMac

iMac from the side

Physically, the Retina iMac is basically the same as the 27-inch iMac design introduced in late 2012. It’s got a bulbous back that tapers to thin edges all the way around. This design has been somewhat controversial, because while Apple’s obsession with making its portable devices thinner makes some sense, a large Mac that sits on a desktop all day doesn’t seem to be crying out for a thinner design.

I have to admit, I’m not opposed to the thin-edged design of the current-model iMacs, including this one. It’s awfully pleasant to grab an edge and turn or tilt the iMac from one of its thin edges. I don’t love that this design has driven the SD card-reader slot from the side of the iMac to┬áits back, but it’s not that big a deal.

But otherwise this iMac is more or less like its non-Retina 27-inch counterpart. In addition to the card slot, there are two Thunderbolt ports (now supporting the speedier Thunderbolt 2), 4 USB 3.0 ports, a headphone jack, and a gigabit Ethernet jack. Dead center on the device’s back is the exhaust fan and, below that, a door you can open in order to access the iMac’s four RAM slots. So, yes, the iMac’s memory is upgradeable by regular people, though not much else is. (iFixIt reports that the processor is replaceable, so maybe people will try to upgrade these things in a few years’ time?)

Now about that fan. I am not among the most sound-sensitive people around, since I’m often working with music playing or headphones in. However, even I notice when I’m recording a podcast and my MacBook Air’s fans are loudly blowing because some runaway app is using way too much processor power. When I ran stress-testing processor and GPU-based tests on the iMac, the fan would definitely come on, and in a quiet room it was audible. It was also, to my mind, vastly quieter than the fan in my MacBook Air. The iMac’s not going to match the Mac Pro for quiet fan blowing, but neither is it going to beat out any Mac laptops in a contest to see who can make the most noise.

It’s faster than almost any other Mac

In its standard configuration ($2499), the Retina iMac is powered by a quad-core Intel Core i5 processor running at 3.5 GHz. Because the high-end Xeon processors that drive the Mac Pro run slower (but have many cores), the old high-end, custom 27-inch iMac configuration was the previous speed champion at running the 64-bit GeekBench single-core benchmark test. The stock Retina iMac beat that iMac’s score, and according to GeekBench developer Primate Labs, the Retina iMac’s optional 4.0GHz Core i7 processor ($250 extra) is even faster. So for single-threaded applications, this is the fastest Mac of any kind.

GeekBench Single Test Results

GeekBench Multi Test Results

Of course, the Mac Pro excels at multi-core performance, and these iMacs can’t quite keep up. The stock iMac got a GeekBench 64-bit multi-core score of 12290, meaning it was slower than all of the Mac Pros and also that custom 27-inch non-retina iMac configuration with the i7 processor. According to Primate Labs, the 4.0GHz Core i7 custom configuration of the Retina iMac is faster than all iMacs and even one of the Mac Pro models.

Cinebench CPU Test Results

Likewise, this iMac showed off well in graphics-intensive tests, though measuring graphics performance on these systems is a knotty problem. The AMD Radeon R9 graphics processors that power the Retina iMacs are impressive—but they also have to drive a screen with nearly 15 million pixels, refreshing sixty times a second. Most of the standard graphics tests one runs to test systems like this involve 3-D rendering at much lower resolutions—HDTV level, not 5K—and presumably those are the resolutions you’d use to play games on this system, too.

Cinebench Open GL Test Results

Unigine 720 Test Results

Unigine 1080 Test Results
Scores for reference systems via Macworld and Primate Labs. Unigine 1080 score was corrected post publication.

As a $250 configure-to-order option, the Retina iMac’s GPU can be upgraded to a Radeon R9 M295X with 4GB of DDR5 RAM, twice as much as the stock configuration. There seems to be a lot of concern about whether the stock video card can really drive the Retina Display, or if it’s underpowered and quirky like, say, the original Retina iPad.

In my use of the stock system, graphics performance was generally fine, though if I opened a whole lot of windows and spaces and then invoked Mission Control, I could definitely see pauses and stuttering. I have no idea how much of that is the fault of the system hardware, and how much is the fault of the software.

I also found that most of the programs I use worked flawlessly on the iMac, but a few—most notably Apple’s own Logic Pro X—stuttered badly when I tried to scroll through a timeline or zoom in on a project section. I worked around Logic’s performance issues through a little-known technique: You can select an App and choose File: Get Info in the Finder, and you’ll see an option to “Open in Low Resolution.” With this box checked, Logic worked just fine on the iMac—albeit without pretty high-resolution graphics.

It’s going to be a tough decision

I’ve been in the market for a desktop Mac for a few months. I began considering the Mac Pro, but the $3000 entry price seemed like overkill. Then I looked at the Mac mini, specifically the quad-core models, but they were outdated—and the newly updated Mac minis only offer dual-core processors. Then along comes the Retina iMac, and even though I’ve got a perfectly nice 24-inch display on my desk, I’m sorely tempted to join the Retina party.

This is the promise of the 27-inch iMac with Retina 5K Display: It’s one of the fastest Macs ever attached to the best Mac display ever. Yes, it’s an iMac, meaning you can’t attach a newer, faster computer to this thing in two or three years. But I have a feeling that these iMacs will have the processor power, and the staying power, to make the aging process much less painful.

In fact, perhaps the most difficult choice when it comes to the Retina iMac is which features to select from Apple’s online configurator. The 3.5GHz i5 processor is pretty amazing, but the 4.0GHz i7 is faster than the low-end Mac Pro. The stock GPU looks pretty good, but the higher-end GPU will probably do a better job pushing around the millions of pixels on the screen.

Throw in extra RAM (though you can add that later, too) and switch from a Fusion Drive to pure SSD storage, and you’re looking at a bill that’s entirely comparable to buying a Mac Pro… but in addition to getting one of the fastest Macs around, you’re also getting a 5K retina display. It sounds like a pretty good deal in exchange for grabbing a slice of the future.

As for me, I ordered the 4.0GHz i7 upgrade with the faster GPU and a 512GB SSD. I pledge my allegiance to iMac Nation. Long may its millions of pixels reign.

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