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USB3.0 Hub - bandwidth usage query

Last response: in Computer Peripherals
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January 9, 2013 2:51:51 PM

Hi all,

I have an alienware m18x which has 1 USB 3.0 port. My USB devices are all still USB 2.0 and currently each one has its own dedicated on board USB 2.0 port.

In order to reduce the number of USB devices I have to plug in each time I move the laptop, im considering moving all my USB devices onto a USB 3.0 hub.

My question is this:

If I buy this USB 3.0 hub and plug it into a USB 3.0 port:

http://www.ebay.co.uk/itm/B-HI-Speed-4-Port-USB-3-0-HUB...

And plug in a wireless keyboard, wireless mouse and sometimes a USB memory key, will all three of these USB2.0 devices be able to transmit data at their maximum speed of (60MB/sec) simultaneously?

ie will they share the USB3.0 hubs maximum upload speed of 625MB / sec?

or will the USB hub switch down to USB 2.0 mode and instead give each of them an equal share of 60MB/sec? (basically making what im thinking about doing - not worth doing)?
January 9, 2013 7:10:35 PM

The usb hub will switch down and give the usb 2.0 devices the speed that they should operate at. A usb 2.0 device is still a usb 2.0 device and is not capable of usb 3.0 speeds.
January 9, 2013 9:02:49 PM

Real world USB2 throughput is actually closer to 35 - 45MB/sec after overheads.

A wireless keyboard and wireless mouse use close to nothing in terms of bandwidth. Certainly nothing close to 45MB/sec.

Most USB2 flash drives also don't get anywhere close to 45MB/sec.

So I don't think you need to be concerned greatly.

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January 10, 2013 8:01:16 AM

OK so no cause for concern in this instance but I would still like to know how is the bandwidth dealt out and how USB 2.0 and USB 3.0 work together....

Does the hub switch to USB 2.0 on its uplink port and therefore share the 35 - 45 MB/sec between all USB 2.0 devices plugged into it or does its uplink stay at USB 3.0 and share the 625MB / sec between all USB devices plugged into it?
January 11, 2013 1:07:42 AM

With all the devices being backwards compatable and you connect a usb 2.0 to the hub you will get the correct bandwidth that the device needs and the hub will be connected by 3.0 and the devices by 2.0. As PasMark has said a mouse and keyboard will use next to nothing for bandwidth and unless your connecting an external hard drive enclosure with a SSD inside you won't have to worry about bandwidth , the hub is designed to give each device it's rated bandwidth.
I fully expect a 3.0 hub to give the appropriate bandwidth to all the 3.0 devices that I connect to it.
!