Plugable 2.0, Horizontal Streaks with Three Monitors


#1

I am running a computer setup with three monitors. The primary is connected to the computer by a VGA cable. The other two are connected by Plugable 2.0 Display Adapter. After the two Plugable monitors have sat unused for a while, horizontal streaks, about 5 pixels long, appear at random places on the screens… Sometimes there are one or two streaks and other times as many as 6 or 7. When I use the monitor and an image crosses where one of the streaks has appeared, it disappears, but might reappear at a different place later. Do you have any suggestions to correct this problem? The computer is a Lenovo Thinkpad T61 (T7700 processor @ 2.40 GHz), with an nVidia Quadro NVS 140M (512 MB). The system runs Windows XP SP3. All three monitors are Samsung SyncMaster 914V set at 1024 x 768 (75 Hertz refresh, 32 bit highest color quality). All of the monitors are using 25 foot VGA cables. The laptop’s display is disabled. Thanks.


#2

Hi Richard,

Thanks for contacting us regarding your multiple monitor setup. We haven’t seen any issues like this before. What stands out as unique is the long VGA cables. Can you try using a shorter VGA cable? If this helps, perhaps a long USB cable could substitute for the long VGA cable.

Let us know if you see any improvement by removing the long VGA cable from the setup.

Hope this helps!
Jerome.


#3

Hi Jerome,

Thanks for the advice. The shorter cables are fixing the problem. I replaced the 25 foot VGA cables with shorter VGA cables and the streaks have almost entirely disappeared. I think if I can make the cables even shorter (like 6 feet), the streaks may disappear entirely. I’ll have to redesign my desk arrangement to accommodate the shorter cables, but it will be worth it to have three monitors. Good idea. Thanks.

  • Richard

#4

Hi Richard,

Glad to hear you have some improvement with your issue. You should be able to extend the reach to the monitor with long USB cables to the Display Adapters and shorter VGA cables from the Adapter to the monitor with out seeing the same noise issue.

Let us know how it goes and thanks for keeping us posted!
Jerome.


#5

OK, the THREE monitor problem is fixed by using shorter VGA cables, but adding a FOURTH monitor makes the problem reappear and in a much worse form. With FOUR monitors, the images on the left-most monitor become fuzzy, wavering, and have streak lines that move horizontally from the image and to the right (almost as if a breeze were blowing pixels off of it from left to right). If I move the image, it leaves streak-lines that do not go away. The image on the right-most monitor is less fuzzy (the words look like they are shimmering, but not as bad as the right most monitor). Also, if I move an image from the left most monitor to any of the other monitors, their images also become degraded. The monitor with the direct VGA connection will suffer from having icons vanish after the image moves over them.

I tried these fixes: (1) Turning the system off (lap top and all monitors), and then switching the Plugable devices but the problem reappears on the same monitors. (2) Going into Control Panel, Display, Settings, and switching the monitor arrangement in the “settings” tab but the problem remains on the same monitors. (3) Going into System, Hardware, Device Manager, Display Adapters, and deleting uninstalling all of the Plugable devices, and then turning the system off and then back on to ensure that the Plugable devices are all deleted in Device Manager, and then turning it off again and making the left-most monitor the one that is directly connected by VGA cable to the laptop, and then turning the system back on and installing each of the other 3 monitors (one at a time, and in their arrangement order) using Plugable. With this fix, there is no problem until I add the fourth monitor, and then the problem appears on both of the last two monitors that I added. It is not as severe as before, but it is still a problem.

By the way, each monitor has 5 buttons, and one of them calls up a menu for configuring the monitor. The menus on all four monitors displays perfectly. Any ideas?


#6

FOLLOW UP: OK, I think I fixed the Four Monitor problem. I noticed that, each time I was adding the fourth monitor, I was adding it onto a USB hub that already had a Plugable device on it. Apparently, the Plugables each need their own USB port. They can’t share a hub with another Plugable. Armed with that information, I tried a new fix: changing my USB configuration so each Plugable has its own port on the laptop. The images are vastly improved. Almost error free (except for the third monitor which is now on a USB hub with my mouse and keyboard). I think that if I continue to tinker with the port and hub configurations, I will solve the problem.


#7

Hi Richard,

Thanks for the update. What you’re describing sounds like a lack of power from the hub. USB Graphics Adapters need up to 500mA each and a USB hub that does not have an external power supply will only be able to supply 500mA split across all the ports. Since each of the adapters operates correctly when plugged in to a USB port on the laptop, It’s very likely that a powered hub will solve your problem. That way each adapter will be supplied the full 500mA it requires.

I hope this helps!
Keep us posted!

Thanks,
Jerome.


#8

Powered hub? 500mA? I didn’t know that. This sounds like a great idea. Right now, with my hubs reconfigured, the system has been working fine (no streaks or image problems) with four monitors, but I would like to add a fifth. The powered hub sounds like the way to go. What is the maximum number of Plugable 2.0 devices I can run on a single Windows XP system?


#9

Hi Richard,

Yep, you’ll want a hub like our http://plugable.com/products/usb2-hub… to provide enough USB ports and power them.

On the USB graphics side, the drivers support up to 6 USB graphics devices on Windows XP/Vista/7.

So with 6 of our adapters, you can get to 7 or 8 monitors total (depending on whether your main GPU has one or two outputs).

Your setup is a nice one. If you have a chance, we’d love a post back here to let people know how things go, once you’re done!

Best wishes,
Bernie


#10

Here’s an update. The powered USB hub did the trick. All of the previously reported problems have been solved, and I am running 4 monitors (3 adapters) with no problem. Thanks again for your help.

  • Richard

#11

Glad to hear it Richard!!!

Let us know if there’s anything else we can help with.

Thanks,
Jerome.


#12