27in iMac APPLE CHOICE
A great upgrade,
particularly if you pick
the high-end options.
Our only wish is for
Apple to make SSDs
the norm for storage.+++++
Big, stunning display
Eight-core Core i9
processor is powerful
Vega 48 is excellent
Roomy SSDs costlyVERDICT
comfort threshold during intense scenes.
Lowering the resolution to 1920x1080
achieved a rate of 77fps – there are still dips,
but the overall result is much smoother.
Memory options
The iMac’s memory is one area that hasn’t
changed much at all, aside from an increase
in clock speed from 2,400MHz in the 2017
line-up to 2,666MHz this year. All iMacs
come with 8GB of memory as standard.
Apple has retained user-upgradeability
of memory on 27in iMacs, through a panel
behind the stand. If you’d rather Apple
installed more for you, it wants £180 for
16GB, £540 for 32GB, or £900 for 64GB (only
offered on the mid-range and top models).
Our review unit came with 16GB as two
modules, leaving two slots empty for further
expansion. Unless you’re running high-end
graphical tasks, working with huge data sets,
or need lots of virtual machines to be open at
once and responsive, 16GB is often enough.
There are significant savings to be had by
adding memory yourself though, particularly
if you want more than 16GB. Bought from a
reputable online retailer, two 4GB modules
(to take the iMac to 16GB) is around £50,
while two 16GB modules (for a total of 40GB)
is around £180. Just make sure you follow
good practice for handling electronics.
It’s good that you can upgrade memory
later if needed. You may decide that you’ll
never need better processors. But we come
full circle to the iMac’s storage. Apple’s prices
for a pure SSD are off-putting when you step
up to 512GB or higher capacities. You may
think you’ll get by with a plain hard disk or
Fusion Drive, but an SSD is the one upgrade
option you shouldn’t ignore.
In 2019, with all MacBooks and the Mac
mini equipped with an SSD by default, it’s
an unpleasant feeling to pay a minimum of
£1,749 for a 27in iMac where you can feel the
Fusion Drive difference in a negative sense.
A problem with going all-SSD on the all-in-
one iMac is how it would sound for Apple to
tell you to buy an external drive. That’s an
easier argument to make with a portable Mac.
We wish the iMac included better storage
by default, even if that were only to restore
the Fusion Drive’s larger SSD capacity, or
offer a small saving by letting long-term Mac
owners leave out the keyboard and mouse to
put the saving towards an SSD. The resulting
responsiveness would make the iMac a better,
more balanced experience that isn’t reliant on
other strengths, like its gorgeous display.Storage in an iMac is tricky to access and not intended to be upgradeable.macformat.com @macformat JUNE 2018 | MACFORMAT | 81The Fusion Drive difference
Apple introduced its Fusion Drive tech in 2012 as a way
to gain some of the benefits of speedy yet pricey SSDs,
but at a lower cost and without sacrificing the large
capacity of affordable (but slow) hard disks.
The tech binds one drive of each type and presents
them as one. It tries to keep the data you use most
often on the SSD. It also keeps a small amount of the
SSD free, in which to quickly create new files. Data it
thinks you won’t need soon is moved to the hard disk.
At first, Apple used a 128GB SSD in Fusion Drives,
but has since reduced it to 24GB or 32GB. So, today’s
Fusion Drives may have to move data more often.
When using a Mac with only a hard disk, you’ve likely
encountered the wait cursor, or beach ball, when trying
to do something on its disk. A common reason is that
the disk has gone to sleep while idle, so you have to
wait for it to spin up again.
That also happens with a Fusion Drive when required
data is on its hard disk. You might encounter this less
on one with a 128GB SSD, as there’s a better chance
what you need is stored on that. We put enough on the
21.5in iMac’s 1TB Fusion Drive to ‘fill’ its SSD.Blackmagic’s Disk Speed Test, which alternately
reads and writes 5GB of data, had peak read and write
speeds of 850.5MB/sec and 1.4GB/sec respectively,
but mean averages were 379.2 and 534.1MB/sec.
The averages are dragged down by regular drops
to the kinds of rates expected from a plain hard disk –
too often they were barely above 100MB/sec. So, we
strongly recommend you buy an iMac only with a pure
SSD, despite the extra cost, to avoid the performance
compromise of current Fusion Drive specs.Image^ cre
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