3 monitors


I run a 64bit windows 7 machine. I bought two pluggable usb video adapters, and hooked them up to two Dell 210PH 23 inch monitors. I also connect one 23 inch monitor via my computer.

I have latest drivers installed. Every time I book up and plug in one plugable adapter, the monitor works fine. However, whenever I try to put in the second plugable adapter, both plugable-monitors freeze up. Can you help me get the 3 monitors up and running?



Thanks for your purchase and for posting your question. I’m sure we can figure it out together and get all 3 monitors working at once.

Before we get too far, I’d first like to confirm a few things:

  1. Can you please tell me which model(s) of Plugable USB video adapters you have?
  2. Can you please tell me exactly which version of the drivers you are running?
  3. When you say the Plugable monitors freeze up, can you please describe exactly what you are seeing (black or blue screens, still displaying video but not updating, whole system locks up, etc.).

This information will help me determine what we should do next to get you up and running as soon as possible.



Thanks for the email. The answers to your questions are as follows:

  1. both adapters are here: http://www.amazon.com/Plugable-Multip…

  2. 5.5.27797 (I may have this number wrong, but I think that’ s right. I downloaded it a couple weeks ago. It was the latest version that was stable, but not the beta).

  3. When I plug one plugable monitor in, either directly into the computer or via my separate powered usb hub, the one plugable monitor works fine.

However, when I plug the second plugable monitor in, all the monitors flickr, the second monitor has the background image appear, and then it freezes with horizontal lines making the image fuzzy. The first plugable monitor freezes as well.

I’ve only gotten the three monitors to work together once. I couldn’t let the computer sleep (otherwise, the monitors froze), so my only solution was to keep the computer awake using a refresh extension on Google Chrome (normal “awake all the time” in Windows 7 didn’t work). However, I needed to take my laptop once with me on the road, and haven’t had success since.


Hi - Thanks for your reply!

The behavior you’re seeing is obviously not normal. We’ll get this figured out.

First, I’d like to confirm or rule out that one of the two USB graphics adapter units might be bad.

Can you mark one of the adapters some way (a piece of tape, or note its serial number), and then confirm that the problem happens in the same way, when you plug in the other USB graphics adapter first? (if the problem happens with either order, then we can suspect something about the overall configuration, rather than a particular unit)

Another quick question: can you describe a bit more about your overall USB configuration? Are you plugging all devices directly into a desktop or laptop? And are there any USB hubs or other USB devices involved?

Thanks for your replies, and for your patience while we get this figured out!


Will do. Am just at the office at the moment, but as soon as I am home, will try. Thanks for your prompt response!



The problem happens in both directions, albeit in different ways. Sometimes one screen goes black, sometimes they both freeze. There doesn’t seem to be any method to the madness :-P.

I’ve tried multiple configurations. I have a laptop with two usb ports (and I need one for my mouse). I’ve tried plugging both monitors into a non-separately powered usb hub, but I’ve also tried plugging into a separately powered usb hub. No luck either way.

thanks for your help.

Thanks for reporting back with these results!

The one screen that goes black - is it consistently one adapter? or both have done it at some point in the past?

I think your tests have pretty much ruled out not having enough USB bus power.

Since the problem only seems to happen when 2 adapters are connected, let’s try to rule out a problem with total desktop/framebuffer size. Can you run a quick test where you 1) plug in one adapter, then set its mode down quite low (something like 800x600) 2) plug in the second adapter, also set its mode low.

Did these steps avoid the problem? (unlikely, but will help rule out that problem).

At this point, what I’d like to do is get you a 3rd test adapter, to see if we can identify one of the units as a troublemaker. Can you email your Amazon order # to support@plugable.com, and let us know if the address from that order is still good.

We’ll get this figured out and solved. Thanks so much for your patience!


Thanks for the prompt reply. I will try the steps above. I have also forwarded my Amazon receipt (the address is still good). Please let me know if you did not receive.

Thanks again for the prompt help. I’m grateful.


Thanks. I did what you suggested above. When I downgraded the second monitor, and then plugged in the third monitor something strange happened - for a brief moment, both plugable monitors worked at the highest resolution. However, almost immediately, but froze in different stages of half pictures/half black streaks. My analog monitor also went crazy too (black streaks), so I had to restart.

Also - one of my units (which I use for the second monitor) goes fuzzy every ten seconds or so for a brief amount of time, even though Ive set the driver to optimized for video. Not sure if this is relevant/helpful.


Hi Kesav,

We’re going to send you that 3rd adapter to help figure this out. Thanks for your patience while it makes its way to you!

Quick note - Having the “optimize for video”, available from the DisplayLink system tray applet, set “on” is what’s causing the fuzziness. This option is off by default, and really should stay off for most users. It’s only useful to turn on temporarily to watch a movie. - and then immediately turn off once the movie is done. When it’s on, text and normal windows, etc. will appear fuzzy for a second every time they move, and only after a delay become clear again.

(it’s effectively an interlaced rendering mode to reduce the load on USB, where all lines don’t arrive until some time later. Looks better for motion video, but worse for everything else).

Thanks for your patience!


Great. Thank you. If you could send me the tracking number when available, I would be grateful.

Good to know re: optimize for video mode. I’ll turn off when I get home.

I’ll be away for the holidays Thr - Sun, so may be delayed in testing unit.

Thanks! - Kesav


Great news. The new unit arrived and it works GREAT! Thank you. The problem is fixed, and I now have three units up and running at the max resolution. It’s awesome.

Thank you so much. - Kesav

P.S. What should I do with the defective unit?

Hi Kesav,

Very glad to have you up and running. We definitely want to get that bad unit back to try to figure out what was causing this strange behavior – we’ll send you a prepaid shipping label this week. Thanks so much for returning it to us for diagnosis!

Thanks again for your patience while we got you fixed up.


Sounds great. More than happy to send back. May be a little slow with New Years and all.

Thanks again. I really appreciate it.


Bernie: bad news. I had to restart my computer for an AVG virus update, and then the same problem returned, even with the experimental unit.

Each monitor works great on it’s own, but when I try to get three working, the two plugable ones end up freezing/appearing with lines/going black. I think it’s a driver issue.

What do you think are the best next steps? any chance you could remote in and take a look? I suspect that would be faster than my taking individual steps.


Ah, what a bummer this is still an open mystery. The suspicion now shifts back to a driver conflict with the system’s main graphics controller (do you know what intel/ati/nvidia graphics controller you have, and what driver version for it?)

Yes - let’s remote in to try to get this nailed. Can you email support@plugable.com and we’ll try to figure out a time that works?

Sorry - but thanks for sticking with this!


I was able to download the new driver put out by displaylink. Now all three monitors are working!

That being written, I’m hesitant to turn the computer off, in case I lose the functionality. One of the monitors plugged in is the test unit.

I’m happy to send my other unit back to you. If you prefer the test unit, let me know, and I will unplug it and use the other one.

So I think I’m good for now - although I will definitely let you know if I end up restarting the computer and am not able to get the monitors up and runing again.

Thanks - Kesav

Hi Kesav - Thanks! Please keep the 3rd adapter - it’s the least we can do given your patience in trying to identify the problem & solution here. Plus, it may be useful if a problem resurfaces.

Thanks again!

Bernie - thank you. That’s very kind of you. I did find the same problem occurring when I restarted my computer, however I had to get to the airport before I could reinstall the driver. I will try that when I get home. All the best. - Kesav