USB4 is theoretically the best of the USB and Thunderbolt worlds. Almost every modern Intel laptop, and more and more AMD laptops, have it, but the situation on the desktop was limited. The reason? The CPU manufacturers are not integrating it into their desktop CPUs for the time being and until now only one chip was available to still offer this functionality: Intel’s Thunderbolt controllers. ASMedia promised more than a year ago to come up with an alternative, but it was only now that I saw it in action for the first time. Later this year, this should become the chip that brings USB4 to the masses.
Intel released the Thunderbolt specification in 2017, almost six years ago to the day. Two years later, standards organization USB-IF officially combined existing USB specs and Thunderbolt into the next generation of USB, which was dubbed USB4. Almost immediately afterwards, controller manufacturer ASMedia, a subsidiary of ASUS but supplier to all motherboard manufacturers, started designing a USB4 chip. A company representative told me that the more than three years of development time was needed because of ASMedia from scratch got to work; the Thunderbolt spec written by Intel turned out to have a steep learning curve.
USB4 plug-in card and ASM4242 controller
At MSI’s Computex booth, I came across a demo setup of USB4. A bit strange, because USB4 with an Intel controller is nothing new. Removing the heatsink from the controller revealed what I suspected: this was the new ASMedia ASM4242 controller, which has been talked about for over a year. It will not only be cheaper than the existing Intel chips, but it will also be technically superior. The existing Intel controllers still use PCIe 3.0 x4, which limits the maximum speed, especially if you want to use both ports at the same time. The ASMedia controller supports PCIe 4.0.
The demo used a prototype USB4 PD100W Expansion Card, a PCIe 4.0 x4 card with two 40Gbit/s USB4 ports and two DisplayPort 1.4 inputs. With the latter two you can loop the image signal from your video card to the USB4 ports. The first port also supports fast charging via USB-PD with no less than 100W (20V/5A), powered via the PEG6 plug on the inside of the plug-in card. The second port supplies a maximum of 27W (9V/3A).
In the demo system, the plug-in card was connected to some kind of external SSD housing, in which a WD SN850X SSD was placed. Although the circuit board of this prototype was inaccessible to my curious hands and there was a heatsink on the controller, I can say with certainty that this USB4 controller also came from ASMedia. I suspect it was an ASM2464PD.
benchmarking
A CrystalDiskMark test showed sequential speeds of over 3700MB/s for both read and write. I was also able to copy a large 40GB file from the external SSD to the system’s internal SSD at speeds of 3 to 4GB/s. That’s significantly faster than what I’ve seen with contrived “USB4” dual-controller SSDs to date. In a comparison of two such SSDs, we never exceeded 3GB/s at the beginning of this year and in practical tests did not even exceed 1.5GB/s.
Availability and impact
The ASMedia controller shown was an engineering sample. Trial production will start in the second half of this year, after which the manufacturer expects that we will actually see products with the ASM4242 on board around the turn of the year, potentially at CES 2024. Although ASMedia is a subsidiary of ASUS, it traditionally supplies all manufacturers. Even now, the company is in talks with all motherboard manufacturers, a representative confirms to Tweakers. The fact that MSI was able to give the first demo also confirms that there is no strong preference for its own sister brand.
I expect that with the availability of this USB4 controller, many more and especially cheaper motherboards than is currently the case will be equipped with USB4 ports. This is badly needed, because so far this feature has only been reserved for expensive high-end models or special ones creator-plates. Especially with motherboards with an AMD chipset, the use of an Intel controller is logically sensitive. The arrival of this chip is also good news for some laptops, because both AMD and Intel have recently been reusing desktop chips for its most high-end mobile processors, and due to that origin Thunderbolt or USB4 support is therefore lacking.
Where you now have to search and spend a lot of money to equip your new PC with USB4, this chip will hopefully ensure that USB4 is just as commonplace on desktops as it is on laptops by the end of the year. That’s great, because that combination of the compatibility of USB and the speed of Thunderbolt is without a doubt the plug of the future.
