all about the screen
Putting aside everything else about the Retina iMac, the real story and the reason you're interested in this machine is the screen.
The iPhone 6 Plus notwithstanding, Apple tends to define "Retina" as a display that has double the pixels of the product's previous (non-Retina) display. Apple doubles the pixels but then adjusts text and graphics so they take up the same amount of space on-screen, keeping things readable.
With the Retina iMac, Apple doubled the 2,560 x 1,440 resolution of the old 27-inch iMac in both directions — to a mind-boggling 5,120 x 2,880 pixels. Apple dubs this 5K, and it's a significant increase over other high-resolution desktops.
With 14.7 million pixels on the panel, Apple says the Retina 5K iMac has seven times the resolution of full HD (1,920 x 1,080). Even more impressive, it has 67% more pixels than a 4K display.
Kent Akgungor put that in perspective when he figured out that you can fit 80displays from the original Macintosh from 1984 into the resolution of the new Retina iMac. That's a lot of display advancement over the last 30 years.
To push all those pixels, Apple had to create its own timing controller. A timing controller, or TCON, is what ensures that pixels light up in the right places at the right time.
Historically, a big bottleneck with displays with this kind of density is bandwidth for the stream itself.
I've tested a few 4K displays in the past and although those displays look great, most use what's called Multi-Stream Transport (MST) to get the image to appear. MST basically outputs two 2K images (a 1,920 x 1,080 screen) and then combines the two images together. MST works fine, but in some applications, you can sometimes see tearing artifacts.
Apple's custom TCON gets around this issue by combining two DisplayPort 1.2 streams onto a single chip. This ends up being 40Gbps (gigabits per second) of bandwidth, which is four times that of the previous 27-inch iMac. As a result, there is no tearing on the Retina 5K iMac and no pauses where the display seems "off." It's seamless.
Apple is also using oxide TFT (thin-film transistor) LCD technology to charge all of those pixels and to make sure they charge faster and last longer. Apple is also using organic passivation — a technique it introduced with the first Retina iPad — to make sure there isn't any pixel cross-talk.
Experiencing the screen
As for the display quality itself, it's an absolute stunner. My first reaction to seeing the screen was to say quite simply, "I want to live in this screen."Blacks are black and whites are white. Colors pop and the tone and calibration are fantastic to the naked eye. Apple calibrates each of its displays before they leave the factory and the results here are fantastic.
The screen is glossy, but not overly reflective. I tested this machine adjacent to a big picture window and although I could certainly angle my head to see reflections in the display, it took a lot of effort and it wasn't evident at all head-on.
Although you can use the Retina iMac in its full 5,120 x 2,880 resolution, most users aren't going to want to do that. The screen real-estate is simply too immense. Instead, the scaled mode, which makes windows and objects the same size as on a traditional iMac, is probably the best bet for most users.
Retina iMac
If you have ever used a MacBook Pro With Retina Display, the experience is very similar. Text is crisp, icons are sharp, and every detail (or pixelated imperfection) is visible.
The nice part about Apple's scaling technology is that video files still play back at their native resolution. As a result, a 1080p video file in full-screen on the Retina iMac doesn't look pixelated or blurry; it looks excellent.
If you want to edit photos or videos, the Retina iMac is a treat. The resolution is so high, you can actually view every pixel of a 4K video clip in Final Cut Pro X, along with the timeline for edits, all in one monitor. That's just phenomenal.
Likewise, anyone doing pixel-precision work, such as illustrators, will love the screen. Zooming in on vector drawings in Sketch or Illustrator is an absolute joy.
Specs
As for the Retina 5K iMac itself, well, it's a top-of-the-line iMac. In fact, core for core, the results were actually better on GeekBench 3 than the 8-core Mac Pro I reviewed earlier this year.
We tested the base model Retina iMac, which includes a fourth-gen Haswell Intel Core i5 quad-core running at 3.5GHz. For the GPU, it includes an AMD Radeon R9 290X with 2GB of RAM. You can upgrade the Retina 5K iMac to a quad-core Intel Core i7 running at 4GHz and you can raise the graphics card to an AMD Radeon R9 295X with 4GB of RAM.
The base system comes with 8GB of RAM, but it can be expanded to 32GB. The system also came with a 1TB Fusion Drive, which combines a 128GB SSD with a 1TB standard hard drive for an experience that offers faster reads and writes for frequently-used files and OS stuff, but uses a traditional hard drive for files that are accessed less often or for media such as music.
The Fusion Drive is a great concept, but for users who value speed above all else, we'd suggest configuring the Retina iMac with an SSD-only option.
The Retina iMac comes with a gigabit ethernet port, 802.11ac, Bluetooth 4.0, four USB 3.0 ports and two Thunderbolt 2 ports, plus an SDXC slot.
Because of the bandwidth required to run the display, the Retina iMac cannot act as a secondary display. That's a shame, because Target Display Mode has always been one of my favorite iMac tricks. Still, it makes sense, especially given the nature of the TCON. It also suggests that Apple might not have a standalone Retina 5K Display until Thunderbolt 3 becomes a reality.
Running Cinebench, the OpenGL results for the Retina iMac are solid. True, this isn't going to be as great as what you could get on a Mac Pro or a higher-end gaming PC, but it's solid.
Performance
I tried to run the Retina iMac through the paces to test its performance. I'm happy to say that even with the base model, it came through with flying colors.
I never noticed any issues with tearing or dithering on the screen. Editing 4K content in Final Cut Pro X with real-time effects was flawless, just as it was on the Mac Pro.
The system never stalled on me, even with two different browsers open and dozens of tabs open at once, along with Final Cut X, Photoshop CC 2014 and other apps running in the background.
The Mac isn't a gaming platform; we know this, but I decided to test out Metal Gear Rising: Revengeance to test the graphical prowess.
At 2,560 x 1,440 (the maximum resolution I could use) and at "ultra" settings, the game remained crisp and solid without any dropped frames. Although I wouldn't say that the Retina 5K iMac is an ideal gaming machine, even the base graphics card managed to keep up. I can only imagine that an upgrade to the 4GB AMD Radeon R9 295X would be even better.
All in all, I have to say I'm impressed with how well the Retina iMac kept up with what I threw at it.
Is it necessary?
A colleague asked me an interesting question about the Retina 5K iMac: Is it necessary? The idea being, do we actually need screens this big with this type of clarity?
Needs are subjective, of course, and it's certainly true that anyone who has an older 27-inch iMac will probably still enjoy the screen and the experience. Plus, although the web is now more Retina-friendly than ever and almost every major Mac app I tested had great Retina support already, it's true that when it comes to video content, 4K and higher is hard to come by.
Netflix offers 4K video on select SmartTVs, but not in the web browser. YouTube offers 4K too, but not for commercial video — plus, YouTube's compression algorithms are far from pristine. iTunes still only offers content in HD, and sure, it looks great on the Retina iMac, but obviously it's not 4K.
It could be fair to say, that at least from a video content perspective, the Retina iMac is ahead of its time. So what's the point? Why did Apple release a Retina iMac now?
Well, to paraphrase George Mallory (and Sir Edmund Hillary), "because it can."
The technical achievement of the Retina iMac is immense. It's a fantastic response to anyone questioning Apple's record on hardware innovation. The fact that Apple was able to get this type of screen, with this quality, working the way that it has in an all-in-one machine is incredible. It's even more impressive when one realizes that the new screen actually uses less power than the older model and that it was able to fit everything into a housing that is incredibly, incredibly thin.
Still, the greatest part is the fact that Apple is doing all of this in something that retails for $2,499. For the same price as a good 4K display (or one of those new 5K displays), you get an entire system — and a powerful system at that.
The Retina 5K iMac might not be necessary, but I'm sure glad it exists.
Final image
As I said at the outset, the real story with the Retina 5K iMac is the screen. The screen is so good, it makes the $2,499 price point seem quite reasonable. If you've been looking for a new desktop and have an affinity for quality displays, the Retina 5K iMac is probably for you. For video and photo editors, depending on what you're doing, the iMac could be a better fit than the amazing Mac Pro.
Even if you're not interested in buying the new Retina 5K iMac, do yourself a favor and check out the display in person at an Apple Store. You can thank me later.
Apple 27-inch iMac With Retina 5K Display
The Good
Amazing screen • Solid performance • Solid price point
The Bad
Can't use as external monitor •Only RAM is upgradeable • Very little 4K content
The Bottom Line
The 27-inch iMac With Retina 5K Display is the most impressive screen we've ever seen and the best all-in-one computer on the market.
Have something to add to this story? Share it in the comments.
