Cables Matter—Test Your Connections

I recently wrote about testing an SSD. As I opened the packaging and noticed the cables that came with it, I started thinking about all the different cables I’ve acquired over the years. While I always try to use the cables that come with equipment, for some reason I seem to end up with extras.

In the past, figuring out cables wasn’t much of an issue. USB and the various flavors of Firewire weren’t interchangeable—their connectors were obviously different. You instantly knew which cable you needed to use. Now, with various iterations of USB and Thunderbolt, it starts to get a little messy because the connectors appear identical.

Just to prove the point, I did some tests with a portable SSD drive.

Speed test results
Speed test results of reading and writing a 4 GB 4K ProRes 4444 file.

The speed using one cable was even slower than some spinning disks. So, then I tried another cable I had lying around.

The only difference between this test and the previous one is the cable.
The only difference between this test and the previous one is the cable.

The difference is dramatic. With the right cable, I was able to get close to the maximum specification for the SSD’s read and write speeds. Even though I used high-performance storage, there was a significant speed difference.

test your connections
With an SSD array, this speed looks okay at first glance.

I tried the same cable test using an SSD array. When the numbers get into four digits, you think you’re doing well.

test your connections
Once again, a change in cables changes the speed.

The only thing I changed was the cable, but speeds increased for both read and write. I could go into a long explanation of what’s going wrong. That explanation would involve comparing various technologies, and it would probably include a rant about how the people naming USB connections keep making things harder.

Unfortunately, since cables aren’t always well marked (the two I used in this test had no markings to differentiate them), it might not provide guidance for all situations.

Instead, I recommend to always test your connections. Software to test drive speed is available, for free, from AJA and Blackmagic Design. Run the test with any new drive and cable combination, and make sure you get the speed you expect. Don’t assume that you’re getting the performance you expect, prove it.

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