Conclusion

USB4 is likely to roll out slowly, although you can already buy products based on the VLI VL830 device controller, and they've been tested and verified to work well with the Intel Thunderbolt 4 controllers. The ASMedia ASM4242 is only just starting to sample to motherboard vendors, so don't expect Socket AM5 motherboards with USB4 support to be among the first boards to arrive once the platform launches later this year. On the other hand, AMD's first Ryzen 6000-series laptops are starting to appear in retail now and will have native USB4 support.

For the near future, the best option will be PCI-Express based USB4 host controller cards, which will let you upgrade many motherboards. There's one caveat though, and that's the requirement for an additional header on the motherboard, just like on Thunderbolt 4. If your motherboard doesn't have that header, plugging in the PCIe card will not work. Display signal mixing will also be handled in the same way as on Thunderbolt, via an external DP cable cable from the graphics card. The reason for this, according to what we were told by ASMedia, is that sending the data over the PCIe bus would use up too much bandwidth, bandwidth which is needed for the USB4 controller.



For those hoping that USB4 would solve the mess that the USB standard has become, the bad news is that some things have gotten even more complicated. There are some minor gains—for example, cables seem to be the last thing to worry about assuming you already own a decent set of USB 3.2 certified cables with USB PD support. Clearer labelling and what appears to be a push towards using the marketing names and displaying them more prominently on products should also make it easier to buy the right product in the future.

As for Thunderbolt 4, it seems like it might end up being the standard for the corporate world, where a lot of the Intel specific management features come into play, and it has lightly better docking station capabilities compared to USB4. The cost difference of the actual peripherals is what will matter here, and if we're going by the first couple of laptop docks based on the VLI VL830, the cost difference will be significant enough that consumers will choose USB4 over Thunderbolt 4 in most cases. The first USB4 docks are about half the price of the cheapest Thunderbolt 4 docks, even if capabilities might not match exactly, but price often plays an important factor in purchasing decisions like this.

As for the future of USB4, well, it'll be tightly linked with what Intel is doing with Thunderbolt 4, and the next step is likely yet another doubling of the data transfer speed. However, this is also where USB4 is about to diverge somewhat from Thunderbolt 4, as from what we've been told, the next version of USB4 might end up getting asymmetric data transfer. The reason for this is that we're starting to reach the end of what copper cables are capable of in terms of data speeds and trade-offs have to be made to reach ever higher speeds. Expect 80 Gbps in at least one direction, with the target for the other direction being 60 Gbps at the moment, over the same cables. This is in part done to enable high-speed data transfer and DisplayPort signals simultaneously without having to compromise the data transfer speed.