Apple upgrades the iMac with a Retina 5K 27-inch screen for $2,499, £1,999, AU$2,999 and shipping now

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 into the premium 27-inch iMac all-in-one desktop.

Officially called the iMac with Retina 5K display, the screen uses a new material, oxide 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 photos and video full-screen. The previous 27-inch iMac had a 2,560x,1440 display, making this jump especially impressive. That 2013 model used an Nvidia GTX 775M GPU for its graphics, 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.

Gaming has never been a big deal on Macs, but the 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 graphical engine here. Intel has a new generation of CPUs coming soon, codenamed Broadwell, but those are now not expected until early 2015 at the earliest. In the meantime, you could 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). The default Radeon R9 290X with 2GB of GDDR5 memory can be upgraded to an AMD Radeon R9 M295X with 4GB of GDDR5 memory for an additional $250, £200, or AU$300.

Storage options in the new iMac with Retina 5K Display start with a 1TB Fusion Drive or a 256GB solid-state drive for the same price, but can be configured with a 3TB Fusion Drive ($150, £120, AU$190), or 512GB ($300, £240, AU$560) or 1TB ($800, £640, AU$960) SSDs. Memory starts at 8GB (two sticks of 4GB), though with four slots total, you can opt to pay Apple for 16GB ($200, £160, AU$240) or 32GB ($600, £480, AU$720).

Other features include 802.11ac Wi-Fi,Gigabit Ethernet and Bluetooth 4.0; an SDXC card slot; four USB 3.0 ports; dual Thunderbolt 2 ports; dual mics, stereo speakers and a headphone jack.

If you've used any of the past couple of generations of 27-inch iMacs, you already know what to expect physically. This is the same design, 5mm thick at the edge, and 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.

Is the iMac in need of a design overhaul? 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 look. If 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.

We'll continue to test the 27-inch iMac with Retina 5K display (as Apple refers to it), benchmarking its performance in productivity applications and games, while also viewing a wide variety of 4K content on its flagship display.

See all of today's Apple news.