Ever since USB debuted, it’s been billed as a simple solution to the complex problem of ensuring device compatibility. While the tendency of USB devices to form quantum superpositions was a problem for nearly two decades, the latest USB-C standard promised to end this, with a single, reversible cable. While it’s a great idea, some problems have emerged thanks to the different types of cables that can all use the USB-C standard.
Here’s the problem, in a nutshell. While USB-C defines a common port, the cables that hook into that port can support a wide range of features and capabilities.
USB-C can be used to handle anything from USB2 communication speeds, to USB 3.1 Gen 1 (aka USB 3.0) and USB 3.1 Gen 2 (the faster variant, with 10Gbps transfer speeds, 15W – 100W of power delivery, and support for Alternate Mode connections). Then, at the top, you’ve got Thunderbolt 3 — a standard designed to vastly increase transfer speeds, that’s capable of driving an external GPU, array of hard drives, or other high-end peripherals.
But therein lies the problem. The actual USB-C cables being sold on the market support a huge range of features. Stephen Foskett published a blog post recently, discussing this issue:
Each one of these cables has a different set of capabilities, and the differences aren’t necessarily apparent to people who aren’t fluent in technology. Up until now, you’ve generally been able to buy USB cables and adapters based solely on price, safe in the assumption that a USB 3.0 cable is a USB 3.0 cable. Now, that’s no longer the case. We can see evidence of how this is shaking out in Apple’s product line. This isn’t to pick on Apple, though I’ve been critical of multiple decisions the company has made — they’re the only company that has adopted USB-C significantly.
We’re seeing a divergence in port support because the underlying standard support is different on different products. The Thunderbolt 3 to Thunderbolt 2 adapter Apple sells doesn’t work on the MacBook at all, even for DisplayPort connections, and even though USB-C has an alternate mode to carry a DisplayPort signal. None of this is terminal, but it means you need to carefully vet cable compatibility when you’re making a purchase.
USB-C cable quality is… less than great
We’ve written about efforts from Benson Leung to diagnose faulty USB-C cables, call out the bad manufacturers, and tell consumers what hardware is worth buying. Both Leung and Verge writer Dieter Bohn lost hardware thanks to faulty cabling, and it’s a significant quality control issue. Nathan K on Google Plus has been building his own extensive database of good and bad cables, as well as deep dives into how USB-C charging is implemented on the Pixel and Pixel XL smartphones. Long story short — despite advertising the capability to charge at 18W, these devices never do unless you literally take steps to force them into using 9V. The 5V option, which is what the Pixel “wants,” tops out at 15W.