Macworld - USA (2019-10-B)

OCTOBER 2019 MACWORLD 23

SSDs. And though 2012 iMacs (anything
with a Fusion Drive and any 27-inch model)
had NVMe connectors, they were only
SATA, so you might as well save yourself
the hassle and upgrade the hard drive to
an SSD.
In 2013, the PCIe bus was deployed,
and though these SSDs were AHCI types,
most of the computers are said to support
NVMe. However, only two or four PCIe 2.0
lanes were used, so you needn’t go
overboard with performance specs—
you’re pretty much limited to 900MBps (2
lanes)/1.5GBps (4 lanes) throughput.
With the late 2015 iMac, the PCIe
revved to 3.0 so you can make use of
even the fastest drives available, such as
the WD SN750 Black that I chose.
As to performance. Much of NVMe’s
kick comes from the insanely quick (10X
SATA) seek times offered by every drive
I’ve tested except one, which was still
three times faster than SATA. The greater
throughput offered by the more expensive
drives only comes into play with larger
transfers. Multiple gigabyte transfers.
If you regularly work with large video
files or write large amounts of data, you
want the pricier types. Also, stay away
from lesser capacities (256GB or smaller)
which often have fewer chips and slower
writes. Avoid QLC (Quad Level Cell/4-bit)
drives and cheaper TLC drives where
throughput drops drastically once they run

out of cache. Check out PCWorld’s SSD

(go.macworld.com/besd) reviews for info

on individual models.

If you do switch out the hard drive

during your upgrade, and find your fans

spinning at full speed, there’s a simple fix

from CrystalIdea called Macs Fan Control

(go.macworld.com/fnct) which allows you

to tweak all of a Mac’s fan settings,

obviating the need for an expensive cable.

PERFORMANCE

I wanted faster and I got it. Big time.

Directly below are the numbers for the

original 24GB SSD. Not bad, but not

bleeding edge by any standard.

Though it was okay in 2015, the 24GB NVMe

SSD that came out of my iMac was slow by

today’s standards, not to mention drastically

undersized. To be fair, it was utilized primarily

as cache for the hard drive.