MacFormat UK – June 2019

Radeon Pro 570X graphics processor, while

the smaller one comes with a 560X. While we

aren’t able to test every single model of iMac,

the Intel processor results for the 21.5in iMac

will give you a rough idea of the range of

capability that’s available in the 27in iMac’s

Intel processor options.

Graphical gusto

Our review unit was also equipped with this

year’s top-of-the-line graphics option for the

consumer iMac range: a Vega 48 processor

APPLE CHOICE Mac hardware

with 8GB of dedicated memory. To check the

capability of this in professional apps, we

ran our recently introduced DaVinci Resolve

test. This exports a 2.5-minute, effects-laden

project to a 1280x720, H.264-format video file.

The Vega 48 excelled at this, wrapping up the

job in just 9 minutes 19 seconds.

Though our historical data for this test is

limited – we only started running it last year

with the Mac debut of external graphics

processor (eGPU) support – the best time on

record had been 9 minutes 50 seconds from

a Core i3-equipped 2018 Mac mini with an

external Vega 64 eGPU. When we connected

that eGPU to this 27in iMac, the built-in Vega

48 still outperformed its time to completion of

10 minutes 42 seconds.

With Mac graphics generally being much

weaker than either of those processors, other

models on which we’ve run this test have

taken much longer to perform it – the Radeon

Pro 560X in 2018’s 15in MacBook Pro took

25 minutes 48 seconds.

We also ran Rise of the Tomb Raider’s

built-in benchmark to judge the Vega 48’s

relative 3D graphics performance. Even with

this processor, curtail your expectations of

being able to run complex games at the iMac’s

full 5K resolution.

Using the game’s High quality preset,

rendering so many pixels brought the overall

frame rate down to an unplayable 23 frames

per second (fps). Reducing the resolution to

match the smaller iMac’s 4K (4096x2304)

resolution raised performance to 34fps,

though with significant dips below the 30fps

BENCHMARKS Our analysis explained

HANDBRAKE

VIDEO ENCODING

We transcode a Blu-ray–quality

video file into H.264 format using

Handbrake to test the multicore

processor performance, which

pushes all cores to maximum output.

GEEKBENCH 4

SINGLE-CORE TEST

This tests the capability of a single

processor core. Many more common

tasks on a Mac will only use a single

core at a time. Intel’s Turbo Boost

technology comes into play here.

RISE OF THE

TOMB RAIDER

For a real-world gaming test, we

use the benchmarking tool in the

game Rise of the Tomb Raider, with

the graphics profile set to High and

the resolution set to 1920x1080.

DAVINCI RESOLVE

In Blackmagic Design’s editing tool

for video professionals, we exported

an effects-laden, 2.5-minute project

to the H.264 format. We limited the

app’s hardware acceleration to use

one graphics processor at a time.

BENCHMARKS Our analysis explained

Index score (higher is better) Duration (lower is better)

6383

5321 16 mins 46 secs

5865 14 mins 41 secs

0 1500 3000 4500 6000 7500 9000 0 5 10 15 20 25 30

Mac mini 3.2GHz six-core Core i7 2018 Mac mini 3.2GHz six-core Core i7 2018

iMac 21.5in 3.0GHz six-core Core i5 2019 iMac 21.5in 3.0GHz six-core Core i5 2019

iMac 27in 3.7GHz eight-core Core i9 2019 iMac 27in 3.7GHz eight-core Core i9 2019

Frames per second (higher is better)

36.7

8.8

0 15 30 45 60 75 90

Mac mini 3.2GHz six-core Core i7 2018

iMac 21.5in 3.0GHz six-core Core i5 2019

iMac 27in 3.7GHz eight-core Core i9 2019

Duration (lower is better)

9 mins 19 secs

25 mins 49 secs

1 hour 26 mins 47 secs

0 15 30 45 60 75

Mac mini 3.2GHz six-core Core i7 2018

iMac 21.5in 3.0GHz six-core Core i5 2019

iMac 27in 3.7GHz eight-core Core i9 2019

9 mins 48 secs

90

77

80 | MACFORMAT | JUNE 2018 macformat.com @macformat

Behind the stand are the

cooling vent and, on 27in

models, access to memory.