Harvey

I notice that you are using a USB Hub that supports 2.0.  The last USB 
Hub I purchased was a few years ago. In researching USB Hubs at that 
time, I found that "supporting 2.0" did not mean that ALL the ports 
supported 2.0. Almost all of the Hubs had 1 or 2 ports that were 2.0 and 
the rest of the ports were 1.1.  I do not know if more recent USB Hubs 
support 2.0 on all ports, but I pass this information on in case it 
might be of assistance.

Tom


On 1/4/2010 9:48 AM, Andrew J. Rozsa wrote:
> At 08:56 PM 1/3/2010, Harvey wrote:
>> I recently bought a Canon CanoScan 8800F scanner and it supports Hi 
>> Speed USB 2.0.  I connected it to my computer a AMD GA-M57SLI-S4 
>> motherboard. When I turn on the scanner I get the message "This USB 
>> device can perform faster if connected to a Hi Speed 2.0 port."
>> How can I tell the speed I'm running at? Since they say that the Hi 
>> Speed runs 40x faster then USB 1.1 there would be a major difference 
>> in performance.
>> The motherboard manual just says it supports 2.0/1.1. The Hub I'm 
>> running it through supports Hi Speed 2.0 and is self powered.
>
> Hi, Harvey
>
> It is my understanding that it all depends what else you have 
> connected to the hub. If one single device is running at 1.1 speed, 
> ALL the devices connected to the same hub will fall back to 1.1. So, 
> although your USB 2.0 is capable of transferring raw data rate at 
> 480Mbps, you might be actually down to a 12Mbps (or less). Since I 
> have some old (but fully functional devices) I have separate exclusive 
> hubs for 1.1 and 2.0.
>
> Also, a USB hub has to re-calculate the time left before the next sof 
> (end of the uframe); the small extra delay added by the hardware hub 
> could make the transaction not handled as fast as a device directly 
> connected to the host. If several devices are connected on the USB hub 
> and working in parallel (for example, a webcam + a USB flash drive + a 
> mouse), then the USB bandwidth is shared among the devices usage. USB 
> hub ports are not as capable or flexible as real PC ports so you can't 
> expect top spec performance from them.
>
> When I built my PC I made sure that I had oodles of internal USB and 
> FireWire ports (8 and 3), so that I can connect critical external 
> devices (like hard-drives) directly to them.
>
> USBInfo & SiSoftware Sandra can report your USB speed status.
>
> Hope this helps.
>
> Andrew
>
>
>
>> HarveyRose
>> [log in to unmask]
>
>

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