Apple's 5K iMac impresses expert eyes

The Good The new 27-inch Apple iMac adds a stunning 5K display for not much more than last year's high-end model. The design, while not updated, remains the gold standard for all-in-one desktops.

The Bad Except for the new screen and a different GPU, the components are essentially unchanged from last year's version. The high starting price only gets you a mid-level Core i5 processor.

The Bottom Line Apple skips 4K and goes directly to what the company calls a 5K display in this expensive, extravagant all-in-one iMac desktop that will appeal to photo and video professionals -- or anyone else looking for the best possible screen resolution.

Just when you thought it was safe to get comfortable with the look and language of 4K, Apple comes along and adds what the company is calling a 5K display in the premium 27-inch iMac all-in-one desktop.

Officially called the iMac with Retina 5K display, the screen uses a new material, oxide-based TFT, and borrowed tech from the Retina iPad to reduce pixel crosstalk to keep images sharp. The panel is also just as bright as the previous-gen model, but uses 30 percent less energy, according to Apple.

In person, that 5,120x2,880 display is simply stunning, especially when displaying high-res full-screen photos and video. The previous 27-inch iMac had a 2,560x,1440 display, making this 2x jump especially impressive. That 2013 model used an Nvidia GTX 775M graphics card, but for the 5K panel, Apple has switched (back to) AMD with the R9 290X. Apple has jumped between these two GPU brands before, and currently, you'll find AMD in the Mac Pro and new iMac, while Nvidia powers the 15-inch MacBook Pro and the non-5K iMac.

Gaming has never been a big deal on Macs, but that graphics-card muscle is vital for video editing and encoding, as well as CAD and design tasks, and that's one reason people choose a 15-inch MacBook Retina Pro, 27-inch iMac, or Mac Pro desktop, all of which include discrete graphics cards.

What you're not going to find here is the latest generation of internal components. Nvidia has new 900-series GPUs for both mobile and desktop, but as noted, AMD is the GPU of choice here. Intel has a new generation of CPUs coming soon, codenamed Broadwell, but those are not expected until early 2015 at the earliest.

In the meantime, you could hypothetically go with Intel's stopgap Haswell-E chips, just announced in August for high-end desktops, but here we've got a standard Haswell-generation Core i5 (with an i7 upgrade for an extra $250, £200, or AU$300).

If you've used any of the recent past generations of 27-inch iMacs, you already know what to expect physically. This is the same design, 5mm thick at the edge, gently bowing out in the back that looks so amazingly thin from the correct angle, and is frankly still pretty thin even in full profile.

This is the third year for this body shape, and the design has made it way all the way down to the base 21.5-inch iMac (or as we call it, the iMac Air). Still, it remains the sharpest-looking all-in-one you can buy, and the amazing 5K display will likely keep you so mesmerized you'll hardly notice anything else about the system.

Is this the iMac for you? If you're a photo or video professional, it's certainly worth a serious look. And, i you fall into that category, there's a good chance you're already eyeing a Mac Pro desktop, although this setup includes a built-in 5K display, and starts at $500 less. If you don't work with the ultra-high-resolution content, or don't sit with your nose inches from the screen, consider the standard non-5K 27-inch iMac, which starts at a more reasonable $1,800, £1,450, or AU$2,200.

Design and features

This is the same chassis as the most recent 27-inch iMac we reviewed, from late 2013. That design blew a lot of minds when first unveiled by Apple in October 2012, as artful photography and clever angles made the system look almost completely flat, although in person the rear panel bows out in the center into a gentle bowl shape.

As we noted of the 2013 iMac, the bowl-like panel and curved one-piece stand make this among the most organic-feeling of Apple's products. That's fitting, as the all-in-one is a desktop subgenre closely associated with family computer use, kitchen PCs, or creative/artistic work, which is a different feel than you get from a no-nonsense tower chassis or an on-the-go laptop.

The iMac still has a collection of rear-panel-only ports and, as with most Apple products, there's no easy user access to components -- except for the RAM, which is accessed via a small panel near the screen hinge. The included Apple Magic Mouse and keyboard are the same as previous models, and you can still swap out the mouse for the Magic Touchpad, my personal preference.

The 5K display, demystified

Let's talk about the real reason anyone is interested in this new iMac, the UHD-busting 5,120x2,880 resolution screen. Can you tell the difference between this and the previous model? Is it worth spending more for the new display? Did Apple skip 4K and go directly to 5K, just as Microsoft skipped Windows 9 in favor ofWindows 10?

We dragged this new 2014 iMac with 5K Retina display into CNET's television testing lab, which is well-equipped for observing and testing displays from 1080p to 4K to, in this case, beyond. There, with the help and observational power of CNET's TV-testing expert David Katzmaier, we set the 5K iMac up next to a 2013 version, which has similar high-end specs (with Nvidia rather than AMD supplying the GPU), and a better-than-HD 2,560x1,440 resolution.

Note that, in this head-to-head, only the 2014 iMac had the latest OS update, codenamed Yosemite, and it's also worth acknowledging that the actual display on our 2013 iMac has been in service for a full year, although we saw no ill effects from that.

The first step was measuring the light output of each display when running a white test pattern, with both systems set to maximum screen brightness. The 2014 5K iMac rated 461.1 nits (cd/m2), while the 2013 version gave us 458.9 nits -- essentially the same light output.

Running through several professional test patterns from our arsenal of television testing files, a set of color bars looked completely identical on both displays, while a grayscale pattern was also nearly identical, but with just a hint of green on the 2014 5K iMac. A multiburst pattern, scaled up from its native 1,920x1,080 format, looked a bit softer on the 2013 iMac, its edges not as sharp or as well-defined.