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I read on https://www.cnet.com/news/usb-4-will-support-8k-and-16k-displays-heres-how-itll-work/ (mirror):

USB 2 reached a data-transfer speed of 480Mbps. USB 3 in principle can reach 20Gbps, though it's most commonly implemented only at 5Gbps or 10Gbps today. USB 4 will be able to reach 40Gbps, the speed of Thunderbolt 3.

Why is USB most commonly implemented only at 5Gbps or 10Gbps instead of 20Gbps?

Franck Dernoncourt
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1 Answers1

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The article is simply misleading. It is a given that “USB 3” is “commonly implemented only at 5 Gbps”. USB 3.0 (5 Gbps) was specified 10 years ago. Uncertified products were available even earlier.

Roughly 7 years ago, USB 3.1 (up to 10 Gbps) was specified.

Only just over 2 years ago, USB 3.2 (up to 20 Gbps) was specified.

It is only natural the vast majority of devices would feature 5 Gbps, simply because it has been available so much longer.

10 Gbps is also well-established by now, though not as much as 5 Gbps.

20 Gbps is not well-established. It is only available on very few motherboards. Devices are even more scarce. Bandwidth this high isn’t needed for most applications. Thunderbolt 3 is a major competitor and features high-performance PCIe access, enabling external GPUs, something USB cannot offer.

My personal take is that USB 3.2 Gen 2x2 is pointless and will never be widely used.

Daniel B
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    I would also add that everything in 10Gbps or 20Gbps probably requires more expensive hardware in pheripherial device. And there is no point to use more than 5Gbps in many devices. – Kamil Dec 28 '20 at 22:40
  • I would add that going from 480Mbps USB2 to 5Gbps is a much more dramatic increase than from 5Gbps to 10, or 10 to 20. The first is a 10x jump while subsequent jumps are only 2x. 5Gbps still allows nearly 500MB/s which for storage is pretty good, but for displays may not be enough. – Mokubai Mar 12 '21 at 10:13