The sails on the CPU rumour mill are really churning at the moment, with reports that AMD's successor to its Zen 4 chip design will be launched this year. New processors also means new motherboards and it's being reported that the top-of-the-line X870E chipset will go one better than the current X670E by offering full USB4 40Gbps connection. However, this will require an additional chip to be added on the motherboard, rather than being part of the X870E device itself.
Take a look at any of the good X670E motherboards on the market right now and you'll see that there are two AMD-stamped chips embedded in the circuit board; one so-called upstream chipset and one downstream chipset. Well, they're usually buried under heatsinks, so they're not always obvious.
Some manufacturers will sometimes include another chip, just to expand the connectivity options. For example, the Asus ROG Crosshair X670E Hero has an Intel Thunderbolt chip for its USB4 ports. For its next generation of motherboard chipsets, AMD is apparently requiring that all manufacturers (via ChipHell) do this for any that will use the forthcoming X870E chipset.
More specifically, it's being claimed that it has to be an ASMedia ASM4242 USB4 master chip, though its possible that other makes could be permitted at a later date.
X670E motherboards are generally quite pricey, with those already sporting a triple-chip chipset configuration being the most expensive. If AMD is going to demand that this becomes the norm for anything using X870E, then the chances of seeing a 'budget' version looks pretty slim.
If all of this is true, it does raise a simple question: Why hasn't AMD included a USB4 controller in its own chips? In other words, why does it need a third party solution?
It's probably down to good old fashioned cost saving. Designing and implementing a USB4 controller isn't quick nor cheap, and it's far easier to just let motherboard vendors use whatever solution they like to add USB4 support. However, in this case it's no longer optional so it will be interesting to see how many X870E board variants we'll actually see.
As to why AMD is apparently insisting on everyone using a specific ASMedia chip, that's probably down to the chipset engineers wanting to design something that will work perfectly, no matter what make or model of X870E motherboard you get. And the easiest way to achieve that is to limit what USB4 chip vendors can use.
If you were looking to upgrade your gaming PC to a Zen 5 Ryzen 9000-series configuration this year, you may want to set aside a little more money than you'd originally planned for. One extra USB4 controller shouldn't cost very much, you can bet vendors will hike up their prices anyway.