iMac Pro review
iMac Pro specs
Build-to-order options let you specify from 8 to 18 cores at 3.2 to 2.3GHz respectively – we tested a ‘sweet spot’ 3GHz 10-core – with 32–128GB RAM, 1–4TB SSD, and either a Radeon Pro Vega 56 with 8GB RAM or a Radeon Pro Vega 64 with 16GB RAM. We’re talking a mix of configs from £4,899 to £12,279 including VAT, just for the core machine.
The workstation-class CPUs are all preposterously powerful, and they support Intel’s AVX-512 tech that allows developers to squeeze even more performance per cycle out of the hardware; we’re likely to see this tech implemented in Apple’s own pro apps first. The 18-core option will likely be most useful in scientific contexts rather than creative.
If it’s formal benchmarks you want, other folks have delved deep into that, but let us give you a flavour: a test we did of transcoding a 4:10-long 4K ProRes clip using Compressor’s Apple Devices 4K and Better Quality 1080p presets as well as its Blu-Ray mastering preset took 7:18 on the iMac Pro, and more than twice as long on a first-gen iMac 5K, which was specced to the hilt and so itself no slouch.
The SSD is silly-fast; in the region of 3GB – gigabytes, not gigabits – per second. This doesn’t just mean fast file operations such as reading untranscoded high-res raw video footage in Final Cut Pro, but also adds to the responsiveness – the perceived speed – of the machine. Apple has achieved this in part by using two SSDs together, controlled by its custom T2 chip (responsible for much else in the system), and though they won’t tell us exactly what they’re doing, only confirming it’s not using one of the RAID standards, we do have some un-answered concerns about data integrity.
The Ethernet ports support 10Gb/sec speeds (10 times faster than the broadly adopted Gigabit Ethernet standard), which is significant if you frequently pull files off a server or SAN – so long as your network infrastructure matches it.
iMac Pro display
In addition to the built-in 5K display, you can add either four 4K displays or two 5K displays. The built-in display is nice, but it doesn’t support HDR (and so if you’re working with very high-end images or footage, you’ll be missing colours unless you add an external mastering monitor), and though it supports P3 colour, this focus on the kind of colour space dedicated to displaying images on screen does come at the cost of poorer colour performance for print-intent work in the Adobe RGB colour space.
Frustratingly – not because anyone in their right mind would buy an iMac Pro just to use as a monitor, but because having the flexibility to do so now, or the option of retiring an iMac Pro to that role after it’s been superseded, is great – Apple hasn’t restored the pre-iMac 5K feature, Target Display Mode, on the iMac Pro. With the 5K, there was a bandwidth issue with Thunderbolt 2 that prevented you from connecting another machine to it and using it as a dumb monitor. But we understand that restriction is gone with the iMac Pro’s Thunderbolt 3, and Apple isn’t telling us if TDM’s absence here is due to technical, political or engineering priorities reasons.
One literal footnote: where before you had to decide if you wanted a VESA mount to allow you add an iMac to a wall mount or adjustable arm (say, beside other displays), it was delivered with one fitted and couldn’t be switched back to use the more usual foot; with the iMac Pro, you can add or remove the foot and VESA mount yourself.