For Computex 2023, MSI is introducing an interesting USB4 PCIe expansion card. The card not only offers two full-bandwidth USB4 40Gbps Type-C ports, but the card can also deliver up to 100W of power to a device connected to it, allowing it to be used to power high-drain devices like laptops.

The MSI USB4 PD100W Expansion Card (MS-4489) has two DisplayPort inputs as well as two USB Type-C connectors. The Type-C ports support USB data rates up to40 Gbps, but also supports DP alt mode and USB power delivery.

What really makes this card notable are those power delivery capabilities; most USB4/Thunderbolt 4 expansion cards are PCIe bus-powered, and can only deliver up to 15 Watts or so. MSI's card, on the other hand, can deliver up to 100 Watts of power on its best Type-C port, which is enough power for charging a high-performance notebook or powering something demanding (e.g., a display). Meanwhile the card's second Type-C port can deliver up to 27 Watts, which is enough for smartphones and other mid-power periphreals.

The card uses a physical PCIe x8 form factor, with what looks to be an electrical x4 interface. MSI has disclosed that it's using a PCIe 4.0 connection, though for they moment they have't disclosed whose USB4 controller they're using. PCIe 4.0 x4 is sufficient to fully drive a 40Gbps port and then some; but it'll fall a bit short of simulaneously driving both ports at their maximum data transfer rates (assuming you even have a workload that can fully saturate the links).

Menawhile, as this USB4 host card goes above and beyond the amount of power a PCIe slot can provide, the card also has a six-pin auxiliary PCIe connector to supply the remaining power. Per the PCIe specificaiton, a x4 card can draw up to 25W from the slot, so the 75W auxillery connector brings the card to its 100W limit. Though this also means that if MSI is sticking to the PCIe spec, then they can't deliver a full 100W + 27W at the same time.

MSI's USB4 PD100W Expansion Card is mainly aimed at users who need to attach bandwidth demanding peripherals (such as direct attached storage or some professional equipment) and USB-C displays to their desktop PCs. The board will serve equally well both the latest PCs that do not support USB4 connectors (or need extra Type-C ports) and machines that are already is use and need to gain advanced connectivity.

MSI does not disclose pricing of its USB4 expansion card or when it is set to be available, though we would expect it to be priced competitively against similar Thunderbolt 3/4 expansion cards that have been available for some time.

Source: MSI

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  • repoman27 - Thursday, June 1, 2023 - link

    Yeah, the x8 physical connector is a real puzzlement here. It gains you nothing in terms of power as x4 / x8 / x16 slots all have the same 25 W initial power up, 75 W maximum dissipation limits. It's even odder when you consider that Intel generally requires Thunderbolt add-in cards use PCIe lanes coming from the chipset and not PEG lanes.

    For those of you who care about the math, per the PCIe spec, this card can pull up to 5.5 A from the +12V rail (which is really the only one we care about in this case) using the card electromechanical connector and 6.25 A from the 6-pin auxiliary power connector. That works out to 141 W, which is adequate to cover the full 127 W Power Delivery budget as well as conversion losses and other board requirements. The controllers and retimers probably have a combined TDP of around 5 W, so thermal dissipation isn't an issue here regardless of form factor.

    This card, like all of the current Thunderbolt 4 / USB4 add-in cards is almost certainly using the Intel JHL8540 "Maple Ridge" Thunderbolt 4 controller, which is a dual-port PCIe Gen3 x4 device. The only thing that sets it apart is that MSI opted for USB4 certification instead of Thunderbolt 4 certification. If they're actually using a different controller, especially if it were one not sourced from Intel, this card would indeed be newsworthy.
  • Exotica - Thursday, June 1, 2023 - link

    I believe this card is not maple ridge, but instead finally signals the arrival of a maple ridge competitor: the asmedia4242 usb4 chip.

    If so, then there are so many questions like: what motherboards/chipsets are supported, will it have dma protection, what are the maximum transfer speeds, what benefits, if any, are there over maple ridge.
  • Exotica - Thursday, June 1, 2023 - link
  • repoman27 - Thursday, June 1, 2023 - link

    Oh, wow, fantastic. Finally a third-party discrete Thunderbolt host controller option! Somehow I missed the news about this a couple weeks ago.

    DMA protection will, of course, be OS and UEFI dependent, but Windows 11 Kernel DMA Protection should work.

    The ASMedia ASM4242 provides a PCIe Gen4 x4 connection to the host, whereas Maple Ridge is only Gen3 x4. And the ASM4242 also supports USB 3.2 Gen 2x2 (SuperSpeed USB 20Gbps) and Thunderbolt 3 Alt Mode for Thunderbolt interoperability. So this definitely looks to have an edge over Maple Ridge, offering capabilities more in line with recent integrated Thunderbolt 4 implementations.
  • DanNeely - Friday, June 2, 2023 - link

    The ~10W of 5V isn't useless. It's needed for back compatibility with low end USB devices. Not what you'd normally use a card like this for, but the support needs to be there. I think the initial negotiations prior to the switch into high power 12V mode probably needs to be done at 5V too (to avoid frying 5V devices with 12V).
  • repoman27 - Friday, June 2, 2023 - link

    There's no 5 V supply rail for PCIe cards though, just 3.3 V and 12 V. There is 3.0 A @ 3.3 V = 9.9 W available, and you're right in that it can be useful, but it isn't being used by the Type-C power path.

    The Type-C ports absolutely have to support the standard 5 V Vbus at 500 mA when connected to USB 2.0 devices, 900 mA for USB 3.x single-lane devices, and 1.5 A for USB 3.2 dual-lane and USB4 devices. Additionally, the USB PD spec requires the 27 W rated port to supply 5 V at up to 3 A and 9 V at up to 3 A. The 100 W port must do likewise and additionally supply 15 V at up to 3 A and 20 V at up to 5 A. However, all of this is being sourced from the 12 V supply rail and converted to the appropriate levels by a buck-boost regulator on the card. The PD controller is likely capable of supplying a very broad range of outputs to support explicitly negotiated power contracts as well, e.g. 3-21 V in 20 mV steps and 0-5 A in 50 mA steps.
  • richardnpaul - Monday, June 5, 2023 - link

    "Meanwhile the card's second Type-C port can deliver up to 27 Watts, which is enough for smartphones and other mid-power periphreals."

    My 150W SuperVOOC charged phone would like a word.
  • hubick - Wednesday, June 7, 2023 - link

    Aren't all the other options tied to motherboards with specific headers/support, which are generally only available for *Intel* platforms? This could be huge for unlocking Thunderbolt for AMD boards that don't support it. Does it support passthrough to external PCIe enclosures?
  • hubick - Tuesday, June 13, 2023 - link

    MSI's press release has a section titled "Intel Z790 MAX Series Motherboard, PROJECT ZERO Back-Connect Motherboard and Expansion Card" that says "MSI brings a unique new motherboard, starting with the popular back-connect motherboard - B650M PROJECT ZERO." talks about the motherboard for a bit, and then says "And also on display is the new USB 4 100W Expansion Card, which allows the motherboard to support dual USB 4.0 40Gb/s Type-C Ports with ultra-high transfer rate and up to 100W fast charging!"

    So, that really seems to sound like this is just yet another expansion card tied to a specific motherboard, and not a general purpose Thunderbolt/USB4 add-in card. :-(

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