Without much fuss, Apple quietly updated the iMac desktop line today, upgrading every 27-inch model to a 5K (5120×2880) display and offering 4K (4096×2304) as an option for its 21.5-inch model.

The 27-inch iMac is a reasonably powerful desktop machine, supporting processor configurations going all the way up a 4.0GHz quad-core Intel Core i7 with Turbo Boost capabilities up to 4.2 GHz. It maxes out at 32 GB of RAM and up to a 3 TB Fusion Drive (Apple's hybrid SSD/HDD storage option) or 1 TB of flash storage.

On the graphics side, the new iMac line is another win for AMD, which provides a range of its graphics cards designed for laptop use. The 27-inch iMac maxes out with Radeon R9 M395X graphics configurable with up to 4 GB of GDDR5 memory.

What's more, the display itself has been upgraded, covering what Apple says is a 25 percent broader color gamut than before. (Apple says the new display has "P3-based" color rather than the sRGB of previous generations.) The 27-inch model can drive up to two 4096×2160 external displays, or one 5120×2880 display (via dual-cable connection), along with the native 5K display. That will come in handy if you're using the system for playback and review in a group. 

On the back of the new iMacs are four USB 3.0 ports, two Thunderbolt 2 ports, a Gigabit Ethernet jack, and an SDXC card slot.

So, yes, the iMac can be a pretty capable machine. However, when we priced out a fully loaded 27-inch iMac with 1 TB of flash storage, it came to $4099, and you can buy a low-end Mac Pro plus a pretty decent display for that kind of money. If you do heavy-duty editing on high-res timelines or 3D work with pro apps that can take full advantage of the horsepower, you'll get a lot of mileage out of the Mac Pro's Xeon processor and dual graphics cards. But for less-demanding applications, the new iMacs look like powerful systems in their own right.