USB Cheat Sheet (2022) (opens in new tab)

PCI-e requires hosts and devices to be backwards compatible, but the interface speed is a required part of the spec. Nobody makes a PCI-E 2.0 device that only works with PCI-E 1.0 encodings/speeds, or anyway, it wouldn't be acceptable.

USB interface chips are, as far as I've seen, a Cypress/Infineon FX3 or a bit more rare FTDI FT600/FT601. I even talked with the FTDI guys at s conference and they said nobody's asking for higher than 5gbps. Infineon just recently, after I think 10+ years, came out with 10 and 20gbps chips. But only for receive. Seems to be for cameras mainly. So surprisingly yes, video production.

But I want it for other reasons professionally. For example, if you look at the signalhound (which uses the fx3) series of products, they often cap out at 40 Msamples/sec for USB. This is a classic 5gbps limit. To compete with the big boys they need 250 MHz if not more. That's 8 gbps before protocol overhead. It doesn't help that USB is extremely dependent on host compute capability to keep throughput up but assuming your PC is up to the task, 20 gbps could interface some serious data to the real world.

Images, videos, movies, file transfer/backup. 50 megapixel RAW images from a DSLR that can capture up to 20 images a second get big. My daughter is a much better volleyball player than I am sports photographer, so I have to spray-and-pray to capture those high-speed hits at the net.

Transferring a few hundred such photos via a card reader was so glacially slow it was worth adding a 20Gbps USB3.2 2x2 port to my home server (Ryzen 5600x) via a dedicated PCI-E card. The USB3 ports on a good enthusiast-class mobo for that generation (only 4 yrs ago) max out at 5Gbps (theoretical). I would have added a 40Gbps Thunderbolt port instead but then I'd have to take a hit on the top speed of my second NVMe drive due to sharing PCI-E lanes.

While the increasing deployment of true USB4 ports is wonderful, it's not quite a panacea. Just because a port is labeled USB4 doesn't mean you necessarily get 40Gbps performance. USB bandwidth is shared across multiple ports via internal hubs and then the PCI-E lanes the hub is connected to might be shared with other peripherals (GFX, NVME, I/O cards). And different USB ports have different trade-offs depending on how they're internally connected, which isn't always documented well by mobo makers.

Sadly, in consumer systems the lack of PCI-E bandwidth can still be an issue if you want your expensive GPU to run maximally fast and have multiple fast NVMe drives. You have to spec your system carefully, get the latest generation hardware or pay 3-4x for HEDT/Enterprise chipset motherboards. Getting even 10s or 100s of gigs of data in or out of a PC reasonably quickly and conveniently has always been a bottleneck that's only getting somewhat better quite recently.

For at least 7-8 years I have been using USB external enclosures for M.2 Key-M NVMe SSDs, which always saturated whatever kind of USB port they were connected to, i.e. 5/10/20 Gb/s.

I do not remember when I have last used a SATA SSD, which is slower than 10 and 20 Gb/s USB, but I think that this was about a decade ago.

Especially once the mass produced cheap stuff starts being churned out, and there's no cost incentive to go back and fix wrong messaging. USB-IF constantly drops the ball around this ngl, feels like they're a pure scientific community that doesn't think about consumer adoption and UX.

Concerning Thunderbolt 3: USB4 is based on the Thunderbolt 3 protocol [1].

Concerning Thunderbolt 4: "In July 2020 Intel announced Thunderbolt 4 as an implementation of USB4 40 Gbit/s with additional requirements, such as mandatory backward compatibility to Thunderbolt 3 and requirement for smaller notebooks to support being charged over Thunderbolt 4 ports.[14] Publications such as AnandTech described Thunderbolt 4 as "superset of TB3 and USB4" and "able to accept TB4, TB3, USB4, and USB 3/2/1 connections"." [2]

Concerning Thunderbolt 5: Intel considers Thunderbolt 5 as an implementation of USB4 Version 2.0. [3]

[1] https://en.wikipedia.org/w/index.php?title=USB4&oldid=134742...

[2] https://en.wikipedia.org/w/index.php?title=USB4&oldid=134742...

[3] https://en.wikipedia.org/w/index.php?title=USB4&oldid=134742...

It's totally not because its density is probably close to lead given the concentration of parts in such a tiny space, with some rubber feat that thing ain't going nowhere.

So it's happening, unfortunately I'm not paying for new RAM. So I'm planning a new rig around my existing CMK64GX4M4A2400C14 sticks.

Type A connectors are typically guaranteed only for around 1000 cycles, with some better connectors rated up to 1500 cycles and some worse connectors rated only for a few hundred cycles.

If you have a device with a Type A connector that you plug and unplug at least once per day, there is a non-negligible risk that the connector will become defective before other components of the device.

On the other hand Type C connectors are guaranteed for at least ten thousand mating cycles, with the best guaranteed for at least twenty thousand cycles, so you should not be able to wear them out through normal usage.

It is true however that you must handle Type C connectors much more delicately than Type A, otherwise you can break them before they are worn out by mating cycles.

During the last few years, high-endurance Type A connectors have also appeared, which can survive a limit between 5 thousand and 20 thousand mating cycles, matching Type C connectors, but most equipment with Type A connectors does not use such more expensive connectors.

Update: USB-PD is a requirement, but manufacturers are allowed to have their own proprietary charging solution.