Conflict when using 2 video adapters on the same USB Host Controller

Using 2 USB 2.0 UGA 2048x1152 adapters on a Vista 32bit dual processor (amd turion 64x2). I was experiencing monitor blinking… like there was a device conflict. Since adding 2 USB plugins to my laptop took half my USB ports I decided to utilize a powered 2.0 HUB. I moved the display adapters to the hub and the the blinking got worse. I decided to try moving one of the display adapters back to being directly plugged into the laptop.

***** The miracle happened *******

No more blinking. So from this observation I’m assuming that there is a device conflict when 2 display adapters are being used on the same USB host controller. I think this is a defect and should be corrected. I can work with your tech support to provide further information or to beta test a fix.


Thanks for posting and sorry to hear you’ve hit those problems with our UGA-2K-A!

We haven’t had any other reports of this problem so far - we have some questions to help narrow this down:

* Can you say which DisplayLink driver version you are using?
* What other devices are connected to the laptop and what devices are connected to the hub ?
* Can you say what is the make/model of the hub ?
* Laptop’s make/model ?

Thank you for wanting to investigate this further! As soon as we have this information we’ll come up with next steps or more questions!


Just to ensure no misunderstanding…the monitor blinking occurred before using the USB hub. I didn’t intend to use the hub to resolve the blinking. I just got lucky.

Displaylink Driver version 5.6.31854.0

Laptop: HP Pavilion dv9500


Other laptop connections:
VGA Monitor
Microsoft USB keyboard/mouse


Thanks for that reply!

We suspect it to be a power issue but cannot be sure.

Can you say which one of VAKOSS hubs do you have as we want to check it’s technical specifications. We can see that only the TC-212-AS has a power adapter and it says that it’s output is 1A. Each port typically requires 500mA - in that case if you have more than 2 devices you may be hitting the hub’s limit.

That still doesn’t quite explain why the UGA-2K-A’s didn’t work when plugged directly into the laptop.

How many ports does the laptop have on each side? What will happen if you hook up each to a different side ? Does it make a difference?


I have 2 ports on each side of the laptop. I just tried your suggestion to plug in a Displaylink on each side. No Blinking :slight_smile:

I didn’t find a model number on the hub, I went to their website. This is the model that looks like mine: TC-271-AA.

It specifies the output power as 1A. I bet you are going to suggest I get a 2A hub?

I responded too soon. Blinking is back. One adapter is plugged into each side of the laptop.


We’re at a loss. If this was a power issue you shouldn’t be seeing it when each adapter is connected on a different side on the laptop.

Can you go to Device Manager and click on ‘View’->‘Devices by connection’ and expand all the way to the hub level and check whether those hubs are on the same host controller or not ?

You should be looking at something like this:

At least we can figure out if the controller has anything to do with it at all.

We suspect that right now, with each adapter connected to a different side they should be on a different controller, but let’s make sure :slight_smile:

Thank you for being so patient!