It gets even better, each function of the port also needs proper support from the cable. Often cables do not support the full spec of usb to cut costs.
While the symbols in the post are often put on computers, for usb cables this is seldom done (only a few brands do).
Source: had to find a cable that supports both DP and PD to connect a portable external monitor after I lost the original cable. (1/9 cables worked)
Yes, this is incredibly annoying and it’s also the reason why some USB cables cost more than others, even they may look the same superficially.
One of those cables that don’t work is rated for like 120W, with gigabit transfer speed… But it refuses to transmit display… Like bruh
That sounds like a dedicated charging cable. So yeah, they will (if at all) only transfer data slowly and not support any extras features like displayport.
For that portable monitor, you should just need a cable with USB-C plugs on both ends which supports USB 3.0+ (could be branded as SuperSpeed, 5Gbps, etc). Nothing more complicated than that.
The baseline for a cable with USB-C on both ends should be PD up to 60W (3A) and data transfers at USB 2.0 (480Mbps) speeds.
Most cables stick with that baseline because it’s enough to charge phones and most people won’t use USB-C cables for anything else. Omitting the extra capabilities lets cables be not only cheaper but also longer and thinner.
DisplayPort support uses the same extra data pins that are needed for USB 3.0 data transfers, so in terms of cable support they should be equivalent. There also exist higher-power cables rated for 100W or 240W but there’s no way a portable monitor would need that.
Yeah, it’s gotten so bad I eventually ordered a USB cable checker to figure out what any given USB cable is capable of (and to see if the cable has gone flaky, which seems to happen a lot). I haven’t received it yet so I don’t know if I can recommend this item, but … gosh darn you sure need something like this.
Sometimes people want to charge their phone in an outlet 10 feet from their airport seat.
Sometimes people want to transmit 8k video.
It’s not physically possible to do both tasks with the same cable.
But because USB is a flexible standard, we don’t have two incompatible specs to do the same thing. So when you get out of the airport and to your meeting, you can actually plug your phone into the meeting room projector for your business presentation. That’s a win.
