Comment by AzN1337c0d3r | Hacker News Reader

Comment by AzN1337c0d3r | Hacker News Reader

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> All USB-C cables do PD. They all do 20V 3A. ALL OF THEM. This is wrong. What FUD.

No you are the one who is wrong. Nothwithstanding optical TB3 cables which can't even carry power, there are a large number of USB-C cables that only do 5V 3A on Amazon such as this one:

https://www.amazon.com/AmazonBasics-USB-C-Cable-USB-IF-Certi...

> There's no mode other than 40Gbps that is official, from what research I've done. But I do see some cables that list as 20Gbps. To me, this seems like a spec violation, but I could be wrong.

https://en.wikipedia.org/wiki/Thunderbolt_(interface)#Thunde...

Intel shipped at least 2 controllers that uses PCIe 3.0 x2, which only allows 20 Gbps.

Here is a CERTIFIED TB3 cable only capable of 20 Gbps:

https://www.amazon.com/Certified-Cable-Matters-Thunderbolt-U...

> In practice, nearly all TB3 cables are 40Gbps capable. They will almost completely certainly run USB 3.2 Gen 2x2 more than fine and will run DisplayPort Alt Mode more than fine. They'll do great.

No they won't. Some don't even support USB 3.0 (5 Gbps), especially if they are longer than 0.5m.

https://tidbits.com/2017/08/23/how-some-thunderbolt-3-cables...

"Instead of carrying up to 5 Gbps of USB 3.1 Gen 1 data, these active Thunderbolt cables throttle down to USB 2.0 speeds, offering about one-tenth as much throughput."

> No they won't. Some don't even support USB 3.0 (5 Gbps), especially if they are longer than 0.5m.

You got me on the long cables. The active TB3 cables are weirder than I thought. I'm not going to hold my breath USB4 fixed this, alas. Other than active long cables, I expect success (although tbh there's numerous beyond-spec (but likely adequate) ~0.8m cables too). As for 20Gbps, that sucks; I thought half-lanes was for ports only, not cables, and had rarely seen (& promptly ignored) 20Gbps cables when shopping. Thankfully these half-breed cables seem exceedingly rare, but yes, a pitfall. I still think your overall premise, "The most capable USB-C cable isn't just a TB3 cable," distracts from just how good an option TB3 cables are for most folks. >95% of TB3 cables on Amazon (old-ish & affordable now) are the most capable USB-C cable, but you've honed in on picky little nits & exceptions & made mountains out of mole hills. I protest; this is immoral.

> No you are the one who is wrong. .. there are a large number of USB-C cables that only do 5V 3A on Amazon such as this one:

I don't get what Amazon's up to, but you'd have to try real hard to make a cable that can do 5V 3A but can't handle 20V 3A. Cables are just not that sensitive to such low voltages, and connectors are too standardized to notice. And indeed, one of the (if not the top) most trusted, thorough, technical cable reviewers on the planet claims this cable is quite good, low resistance, and showed it doing 20V 3A just fine. Perhaps Amazon just lacked test equipment to confirm 20V, but whatever the case, to fail 20V would be difficult to pull off. https://www.amazon.com/gp/customer-reviews/R2DXKTH7UAJIZ4/re...

Re-asserting: no, you do not need special cables for USB-PD. If a USB-C cable can't do 20V 3A, it's broken & out of spec & not USB. You're wrong & USB-C & the Type-C connector in general does not deserve this baseless & incorrect slander.

> Re-asserting: no, you do not need special cables for USB-PD. If a USB-C cable can't do 20V 3A, it's broken & out of spec & not USB. You're wrong & USB-C & the Type-C connector in general does not deserve this baseless & incorrect slander.

USB-C spec doesn't require cables to support PD. You're wrong.

https://www.reclaimerlabs.com/blog/2017/1/12/usb-c-for-engin...

"Even without supporting USB Power Delivery, it is possible to get as much as 15W through the USB connector. VBUS is still limited to 5 Volts, but the current can be as high as 3 Amps."

The quote you're citing is chiefly discussing what happens if you use a charger or device doesn't have USB-PD support. Perhaps there are some cables somewhere if you search long hard. Perhaps. But again you're dealing in extremely rare & exceptional cases & sowing doubt, where I really don't think any such misgivings are deserved. I dislike seeing such unfair maligning & sowing of doubt. I do not think this sense of fear & afraidness is reasonable. A USB-C USB3 cable without CC lines is out of spec & cannot be called such.

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