PC World - USA (2020-02)

62 PCWorld FEBRUARY 2020

REVIEWS WD SN550 NVME SSD

PERFORMANCE

While the 1TB Blue SN550

I tested didn’t excel at any

one task, it handily

outpaced the older

SN500 and was

competitive with its peers

throughout. The synthetic

CrystalDiskMark and AS

SSD benchmarks rated it

as average for its class, as

did our 48GB/450GB

copy tests.

I’ve seen TLC-NAND

based NVMe SSDs

plummet to SATA III

speeds during long writes. While the SN550

dipped to 835MBps rather rapidly, that’s as

low as it went and still what I’d consider

decent performance. Better than SATA, at

any rate, and considering you’ll see

1.75GBps during normal, shorter writes,

perfectly livable.

I did not test the 500GB SN550. If WD is

assigning secondary cache as a fixed

percentage of total capacity, as it seems, the

500GB drive will drop to around 835MBps

even sooner than the 15GB mark at which the

1TB capacity slowed.

The 250GB version of the Blue SN550 is

rated for a little more than half the write speed

(950MBps max), as it has fewer channels for

transferring data. It likely has less cache as

well, so you will not get nearly the same write

performance. Reads, which are not cache-

dependent, nor so reliant on multiple

channels, will be every bit as fast as the

500GB and 1TB capacities.

The Kingston KC2000 (go.pcworld.com/

kc20) led real-world performance in our

The 1TB SN550 runs out of cache after only 15GB

or so, but the sustained 850MBps write speed is

still quite good for a budget TLC NVMe drive.

Sequential W(Q =32, T=1) rite

Sequential Read (Q =32, T=1)

CrystalDiskMark 6

(MBps)

1,457

1,979

3,232

LONGER BARS INDICATE BETTER PERFORMANCE

Addlink S70

WD Blue SN550 WD Blue SN500

Kingston KC2000

2,335

1,720

2,369

3,454

2,474

While the Addlink S70 is a standout in this test, this is a very short

burst of data and the SN550 bested it in real world copies.