Does USB 2.0 slow down with slower devices connected

Discussion in 'Mac Accessories' started by chefwong, Oct 26, 2008.

  1. chefwong macrumors 6502

    Jan 17, 2008
    for example -

    USB 2.0 hub

    3 USB 2.0 devices
    2 USB 1.0 devices

    Does the whole entire USB *chain* slow down by the slowest denominator ?

    In my application, it won't be much.

    1 wired keyboard, 1 wireless transmitter for wireless mouse, 1 epson letterhead size scanner and a compact flash UDMA reader. Maybe a inkjet printer - maybe not -- Epson 3800.
  2. EdbBob macrumors member

    Oct 25, 2008
    I'm currently experimenting with a usb flash raid (read my thread "poor mans ssd"). From my USB experiences it's more like the opposite. Try to open "About this Mac" in the Apple menu. Chose "More Info..." That opens System Profiler. Now chose Hardware/USB. On my iMac7,1 i see two High-Speed Busses (480 Mb/s). If you expand by clicking the small triangel to the left you can see what devices are connected to what bus. Pretty cool...

    I'm an old PC geek so i use a Logitech gaming mouse wich runs 12 Mb/s. That doesn't affect the bus wich also runs a WinTV HVR-900 usb tv tuner running 480 Mb/s :)

    If you're looking for max. USB performance tjeck that the usb devices using most bandwith are at separate busses. I'm trying to build a USB flash raid0 wich uses the two differnt busses and 8 fast USB momory sticks. You can easily run OS X from a raid of 3 stick and again the mouse only runs 12 Mb/s but I'm ready to read 50 MB/s from the raid.

    Hope this helps answer your question ;)
  3. kolax macrumors G3

    Mar 20, 2007
    Yes. If you connect any USB 1.1 devices to your USB hub, the speeds of all devices will be brought down to USB 1.1.

    Avoid connecting USB 1.1 devices to a hub if you want to retain as much speed as possible.

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