cross-posted from: https://lemmy.ml/post/9114359

My motherboard provides 4x USB 3.2 Gen1 ports for rear I/O and another 2x USB 3.2 Gen1 ports for front I/O (through the header), but my chipset only supports 2x USB 3.2 Gen1 ports. Where is the support for the other ports coming from?

Motherboard Wikipedia
Motherboard rear I/O: 2x USB 2.0 ports, 4x USB 3.2 Gen1 ports, 2x USB 3.2 Gen2 portsMotherboard headers: 4x USB 2.0 ports, 2x USB 3.2 Gen1 ports Wikipedia B450 chipset: 6x USB 2.0 ports, 2x USB 3.2 Gen1 ports, 2x USB 3.2 Gen2 ports

The motherboard is an ASRock B450M Steel Legend

  • SomeoneSomewhere@lemmy.nzEnglish
    4·
    7 months ago

    I think some of the USB ports come directly from the CPU, others come from the chipset. This allows the dirt-cheap A300 boards to operate with no chipset at all but still have a couple of USB ports, and likewise with laptops.

  • Septimaeus@infosec.pub
    3·
    4 months ago

    Likely SB chipset but also, vendors sometimes use an extra 4 lanes of PCIe for miscellaneous additional unswitched I/O, including USB (which might be a useful expansion but otherwise just means fewer m.2 slots).

      • Septimaeus@infosec.pub
        2·
        6 months ago

        lol yes, right next to the IDE connector. Nah I meant from the chipset. Here’s the doodle from my mainboard manual for example.

        aorus b650i chipset diagram

        • glibg10b@lemmy.mlOP
          2·
          7 months ago

          Ah, so the chipset uses a few PCIe lanes from the CPU for some USB controllers, and the other USB controllers use dedicated USB lanes coming from the CPU?

          • Septimaeus@infosec.pub
            3·
            7 months ago

            Right, the CPU has a number of standard I/O controllers onboard including USB. No PCIe lanes required for these IIRC. They live on the die itself, often adjacent to the PCIe controllers.