Issues running Displaylink devices through a USB hub

[CanadianFawkes]

I'm trying to run 2 displaylink devices through 1 usb hub and am having issues. Everything runs fine with one device, but as soon as I plug the 2nd device into the hub, the first display starts making a high pitch noise and the pictures gets wavy. I don't have this issue if I use the hub for 1 device and plug the 2nd one into the computer itself. This is the case with both my win7 desktop and my winXP laptop.

Are there any limitations to using displaylink devices through a hub that I'm not aware of? Is it perhaps because my hub isn't powered? I'd like to use two of the 14" Toshiba PA3923U-2LC3 screens but because each requires 2 USB connections I want to run them via a hub.

Thanks!

[Wim]

These Toshiba screens use over 5W (the maximum power that can be delivered by the USB standard). They are shipped with a dual cable so you can use the power from 2 USB ports to power the screen.

However most USB ports will allow more than 5W to be delivered, so you can probably get away with 1 USB connection for a screen and get enough power.

However if you run it through an unpowered hub, you will only have 5W (maybe a bit more) for all the hub ports. This will not be enough for 2 of these Toshiba displays. I'm surprised 1 works when you consider that the USB hub also needs power.

You will need a powered USB hub to make this work, and make sure that the USB hub can deliver 5W out of all hub ports when fully loaded.

Wim

[CanadianFawkes]

Thanks! I picked up a powered hub and they worked great! It's too bad that these screens have such a lousy viewing angle and bleed so much light through.