05-01-2013, 04:56 PM
USB ports are all individual, not connected in parallel. Provided drivers are available the PC should recognise each of the connected devices however they are connected. It's worth remembering however that the USB 2 spec allows 500mA per port to power devices. In practice more current can be drawn. This can be a problem with some USB powered hard drives as the start up current can exceed the maximum current especially on laptops where power is limited. If you are using a hub and connecting USB powered Hard drives then it must be powered from an external supply otherwise you'll only have about 100mA per port available.
The latest USB3 spec, apart from upping the data rate to 4.8GB/s from 480MB/s, increases the power available from each port to 900mA which should be OK for powering USB powered Hard drives. It can cause a problem if a USB3 drive is connected to a USB2 port as it may be expecting to draw up to 900mA, when spinning up the disc, causing the drive to fail to spin up and be fully recognised by the PC.
Keith
The latest USB3 spec, apart from upping the data rate to 4.8GB/s from 480MB/s, increases the power available from each port to 900mA which should be OK for powering USB powered Hard drives. It can cause a problem if a USB3 drive is connected to a USB2 port as it may be expecting to draw up to 900mA, when spinning up the disc, causing the drive to fail to spin up and be fully recognised by the PC.
Keith
