How to declutter your USB cables
Has your USB-C cable collection become as bloated as mine? If so, you’d be better off using just a few and throwing out the rest. That being said, finding the best cables to hold onto isn’t always easy.
Every new device comes with a new USB cable, making the cables in your drawer multiply over time. Conveniently, they’re now always USB-C cables, meaning every connector fits into every port. In theory, that means it’s possible to use the same two or three cables for everything.
The trouble is, USB-C cable types vary significantly, so not all of them boast the same charging speeds or data transfer rates. In fact, you can get anything from zero data transfer to high-speed transfer, as well as massive variation in charging speeds. Oftentimes, you can’t tell how good a cable really is.
To achieve a certain charging speed or data transfer rate, the ports at both ends as well as the cable have to support the right standard. Otherwise, charging or transfer performance drops to the next level down that’s supported on all sides. In other words, you’ve got to make sure the cable’s never the weakest link in the chain.
You’d be forgiven for assuming that if a product comes with a cable, that cable would be enough for said device. Unfortunately, though, that’s not always the case. Take Apple, for example. Although the iPhone Pro comes with a cable capable of USB 2 speed (480 Mbit/s), the phone can transfer much higher data rates (10 Gbit/s).
Assuming you have several, maybe even dozens of USB cables lying around at home, how do you find out which cable’s best for which devices?
Get rid of your USB-C to USB-A cables
Devices are often supplied with a cable that has a USB-C connector on one end and a USB-A connector on the other. While these cables probably perform well enough for the device they’re included with, they reach their limits pretty quickly and aren’t suitable as all-purpose cables. If you can, try to always use cables with a USB-C connector at both ends.
Update: Now that several people have commented on this point, let me clarify what I mean by «If you can». Unfortunately, many devices can only be charged with a USB-A to USB-C cable. So make sure you check that your device can be charged with a USB-C to USB-C cable before getting rid of your USB-C to USB-A one.
USB-A is fundamentally limited. Type A connectors sporting a white or black strip only support USB 2.0. Ones with a blue strip are at least USB 3, meaning they’re capable of five or ten Gbit/s.
You can’t expect much from them when it comes to charging either. Unless it’s a special Power Delivery model, a USB-A cable only manages five volts and three amps, i.e. 15 watts. A standard USB-C cable, on the other hand, can deliver as much as 60 watts.
Hellish USB designations
While we’re on the subject of USB-C only cables, we unfortunately need to take a closer look at USB versions. Which, incidentally, are a pain in the butt. Designations like «USB 3.2 Gen 2×2» are confusing enough in themselves. Mind you, they’re apparently not confusing enough for USB-IF, the organisation behind the specification. It started changing USB versions after the fact, meaning USB 3.0 became USB 3.1 Gen 1 and later USB 3.2 Gen 1×1. So when you come across the term «USB 3.1» somewhere, you don’t always know what it means. In fact, this always applies to USB 3.2; to figure out what a cable can really do, the designation needs to be more precise.
The speeds mentioned in the table are theoretical maximums that are never achieved in practice. They’re mostly useful for comparing versions with each other.
There’s a separate standard for charging speeds, known as USB Power Delivery (PD). Its version numbers are independent of the USB standard. So version USB PD 3.0 version has nothing to do with USB 3.0.
In other words, there’s no direct link between the USB version and charging power. For instance, Apple’s USB 2.0 cable with a lousy data transfer rate charges at up to 240 watts, a peak value.
Then there’s Thunderbolt, a transfer protocol that was originally unrelated to USB. When version 3 came out, however, Thunderbolt started using USB-C as a connector. USB4 is based on Thunderbolt, but there are hidden pitfalls when it comes to backwards compatibility. More on that later.
Markings on cables
Fortunately, some cables are labelled. Thunderbolt-enabled USB cables usually have a lightning bolt symbol and a number indicating their Thunderbolt version, such as four or five. The Thunderbolt standard has relatively strict minimum requirements and requires mandatory certification, so these markings are genuinely worth something.
Older cables are sometimes marked with «SS», meaning «super speed». Cables with this label achieve at least the speed of 3.2 Gen 1×1 (formerly USB 3.0). In other words, 5 Gbit/s – or possibly more. This is sometimes indicated by a plus sign, sometimes not indicated at all. The plus stands for 3.2 Gen 2×1 (formerly USB 3.1), i.e. 10 Gbit/s.
While these speeds may not be «super» by today’s standard, they’re still significantly faster than USB 2.0. The super speed logo’s appearance has changed over time too. You now see SS labels that include a number such as five, ten or 20, indicating the data transfer rate in Gbit/s.
Since 2024, it’s become more common to see USB cables with labels that you don’t need specialist knowledge to decipher. In other words, the data transfer rate and charging speed are printed on the cable. However, there are still plenty of cables on the market that aren’t labelled like this. Including ahem Digitec’s own-brand cables.
Internet research
Some cables have a device manufacturer’s logo or name on them. Sometimes, you can tell which device matches a particular cable based on appearance. The brand of my camera, for example, is written on its cable. Plus, the manufacturer states which cable model it is, so you can look up the specs online. If you’ve forgotten which device matches with a particular cable or vice versa, the search function in your Digitec or Galaxus order history might help you.
As for me, I could count the number of clearly identifiable cables I have at home on one hand. When it comes to the rest, it’s either unclear where they’re from or the information’s unhelpful. These cables call for different methods.
View connections on your computer
You can view information on existing USB connections on your computer. On Macs, the pre-installed «System information» app shows you each port’s USB version number and speed. The USB Connection Information app, available for four francs or five euros, provides more information, for example about charging speeds. It displays the USB version, speed, charging standard and more in a menu. You can also freely configure the display.
If you’re looking for a Windows program, a freeware app called USB Device Tree Viewer displays a wide range of information, including USB version, maximum speed and power usage.
To test a cable, you need to connect it to two devices that meet the very highest standards. That’s the only way the tools will show you any difference if you’ve connected a better cable. Always connect the devices you’re using for your test directly to your computer – never to a USB hub.
Even if you get this right, the method can produce incorrect results, especially with Macs. The ports on newer Macs support Thunderbolt 4 and USB 4, but not USB 3.2 Gen 2x2. As a result, the speed doesn’t exceed USB 3.1 (= 3.2 Gen 2×1) unless Thunderbolt 4 or USB 4 is supported by every device involved.
Measure real speed with a benchmark tool
The same goes for benchmark tools. Tools like CrystalDiskMark read and write test data to a connected storage device and show you the actual data transfer rate. This tells you the real speed achieved, not just the theoretical value. Again, you’ll only spot differing data transfer rates between cables if your SSD and computer support all fast standards. That means the constraints on Macs apply in exactly the same way. What’s more, you can’t use an SSD that’s overheating or almost full.
Real measured values are always significantly lower than what the specs say are theoretically possible.
Sadly, USB cable testers aren’t a viable shortcut
Before I started writing this article, I thought a special USB cable testing device would be the solution. I’d simply plug a USB cable into the measuring device and hey presto, it’d show me the data rate, USB version and charging speed.
Unfortunately, things aren’t that simple. The device measures power, but not data transfer rate. It’s hooked up between the charger and the cable you’ve connected to the device that needs charging. Once you do that, it displays volts, amps and watts. Side note: volt measurement is the only constant value. Meanwhile, the ampere and watt measurements change depending on the battery charge level.
As we’ve already mentioned, it’s rare for a cable to be the weak point in the power delivery process. A typical USB-C cable can manage as much as 60 watts or 20 volts, so you only need a special high-performance cable if your device requires more than that. I don’t own any devices capable of drawing more than 60 watts when charging.
There’s no direct link between the USB version and charging power.
The Treedix cable tester board gauges which pins in a connector are active. This allows you to figure out which USB or Thunderbolt version a cable’s using – and whether it’s still working properly. However, it can’t determine a cable’s effective data rate. The same goes for the cable tester described in the video below. It’s only distinguishing characteristic is its higher price tag – and the fact it presents its results in a more attractive, more understandable way.
Verdict: the worst cables are easy to find
A USB connection, whether it’s for power or data, is only as good as its weakest link. If you have cables with a USB-A connector at one end, you should only hang on to them for compatibility reasons. Especially if they don’t have a blue bar, in which case they only support USB 2.
Cable testing and benchmark tools make it easy to identify the «bad eggs», such as USB-2 cables or cables that don’t allow data transmission. It’s more difficult to differentiate between good and very good cables. When trying to do that, you need devices at both ends that support all of the more efficient standards. Macs are unsuited to conducting tests like these. On Mac devices, fast transmission’s enabled by Thunderbolt, and Thunderbolt cables are clearly labelled as such.
As things currently stand, it’s extremely confusing that there are numerous USB and Thunderbolt versions. However, there’s hope that things will improve in future. Compatibility issues between Thunderbolt and USB are on the decline, while clear cable labelling seems to be becoming more established.
David Lee
Senior Editor
David.Lee@digitecgalaxus.chMy interest in IT and writing landed me in tech journalism early on (2000). I want to know how we can use technology without being used. Outside of the office, I’m a keen musician who makes up for lacking talent with excessive enthusiasm.
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