What’s the Best PC for Running Multiple DisplayLink USB Monitors?

One of our customers is building a six monitor setup on their PC for stock trading and ESignal Qcharts.

They asked: “What is the best Windows laptop and/or desktop to run six Plugable USB graphics adapters to get six monitors simultaneously on a single PC?” It’s a great question, because there are definitely ways to head off potential problems when you pick a PC. It really comes down to two main things to think about.

Intel Graphics Controller

First, for maximum compatibility with USB graphics products, pick a system with Intel-only graphics if possible. Here’s why:

  1. ATI and nVidia, because they’re shooting for the higher end, do more out-of-the-box things to try to differentiate their technology and software drivers. Sometimes those things can conflict with other complex software, like DisplayLink’s USB graphics drivers.
  2. In particular, look out for “switching” or “hybrid” graphics on laptops. These add a discrete nVidia or ATI GPU on top of the Intel GPU already in the chipset, for the purpose of providing switchable “high power” and “low power” graphics by enabling or disabling one or the other GPU. They attempt to do this switching without Windows noticing (just Like DisplayLink tries to add USB display outputs to the primary graphics controller without Windows noticing), but in combination this can cause conflicts. DisplayLink has made some progress with compatibility with these types of systems, but it’s still the #1 hardware compatibility issue we see for USB graphics.
  3. Even though nVidia and ATI provide higher 3D performance, they don’t have higher performance everywhere: in particular with USB displays, the rendered pixels must be transferred from the GPU back to the CPU to be sent over USB. When the GPU has its own memory on the other side of the PCI bus (as is the usually case with ATI and nVidia), those transfers back can be slow. With Intel chipset graphics, the pixels remain in system memory the whole time – which ends up being faster overall.
  4. Intel is in closer collaboration with DisplayLink than nVidia or ATI has been.
  5. Intel’s is the lowest cost solution. For business applications (like stock trading) with many displays, it makes sense to favor simplicity and compatibility over 3D gaming performance.

nVidia and ATI/AMD are great companies that produce high-performance products, and DisplayLink’s software rarely have problems with them. But as it happens the simplest and lowest cost solution is also the best choice for this particular application.

Mid-range or better CPU and Memory

Second, for the system itself, more memory and a faster CPU make a difference. Take the money saved on a high-end 3D processor, and funnel it back into the main CPU and memory that’ll make everything on your PC faster. But no need to go overboard – there’s usually a sweet spot.

For memory with Windows 7 and something like 6 USB displays, 2GB is enough .. although going to 4 or more will produce noticeable overall system gains (mostly because of all the additional apps you’ll be running to display on all those monitors). Even though Windows 7 is much improved over Vista, multiple monitors and many open applications still consume a lot of memory.

But just as important as the amount of RAM is the amount of cache. In the USB graphics case, memory and the memory controller is getting a lot of use, as pixels change on the screen (at least 4 times – when an application renders new pixels, when those pixels are composited on the desktop, when they’re copied to a shadow framebuffer, and when those changed pixels are compressed into USB packets). Note that once the changed pixels are sent over USB, the CPU isn’t involved anymore to refresh the display .. that work is all done by the hardware framebuffer on the USB device, so in terms of CPU load, it’s just about the pixels that are changing at any given moment.

So what to look for in the CPU’s memory controller? Faster memory interface and larger caches. Products change quickly, but currently Intel’s “Nehalem” microarchitecture provides the best alternatives. The sweet spot currently is with DDR3-1066 memory interface or better and at least 3 MB L3 cache. In terms of particular CPUs, that maps out to Intel CPUs like the the Core i3 530 or higher for the desktop, and the Core i3 330M or higher for laptops.

Hope that helps. Feel free to comment if you have any questions.

10 comments on “What’s the Best PC for Running Multiple DisplayLink USB Monitors?”

  1. Alexander Todorov Reply

    Hi Bernie,
    nice guide to purchasing a PC for using with DisplayLink. I’d like to share some things from my experience and observations on Linux.

    1) Use 32bit OS and software. While 32bit systems can address up to 16GB or RAM using PAE, system libraries and applications take less space in memory compared to 64bit systems. I did a test of 16 separate users running OpenOffice.org, GIMP, Eclipse and several other aplications on the same system. On 32bit system with 8GB of RAM around 50%-60% was in use when all users were running all applications. On the same system running 64bit OS and software and the same user scenario the memory usage was nearly 90%.

    2) On newer Linux platforms there’s a feature called KSM – sharing identical memory pages. Haven’t testing this yet but depending on your use case this can also reduce the memory utilization.

    3) To cut down on cooling and power costs prefer USB hubs/adapters that are powered via the USB bus when possible. This will save you around 10 W per display/seat configuration.

  2. LCD Display Reply

    Hi Mate,

    I have windows 7 and 6GB RAM on a custom built i7 PC and I can run two screens just fine on it without any change in performance.

    I know that’s not quite the same as 6 monitors but I would love to give 6 monitors a shot on my PC to see if it drops the performance at all 🙂

    • Mark Reply

      Hi, I’m difficulty finding a right choice for my future multiple HDTVs for Internet TV.

      Could you able recommend a best hardware/software from stratch.

      I appreciate your feedback.

      Mark

      • Bernie Thompson Reply

        Hi Mark – Are you looking for replicating the same video on multiple HDTVs (which I’d recommend an HDMI splitter), or are you looking for each TV to be an independent dislay/video — which would be a tougher case, since USB is the easiest way to add multiple screens to any PC, but it doesn’t have enough throughput (480Mbps theoretical, ~330Mbps practical) for motion video scenarios.

        So there may not be a magic bullet. Which scenario are you shooting for?

        Thanks!
        Bernie

  3. Christopher Scott Reply

    OK,i am looking to run at least 3 monitors off my i3 asus.I will be using it to view mutiple charts while trading the market.Please just reasure me i will not be disapointed if i purchase 3 or 4 of these.
    Thanks,
    Chris

    • Bernie Thompson Reply

      Hi Christopher – that scenario on that class of system is what this kind of hardware is great for. If you reply with the model of Asus laptop, we’ll also check which GPU it has and confirm that’s problem-free.

      And in general, Amazon ships quickly and processes returns without hassle – so a good strategy is to buy one just to test on the system and reassure yourself about compatibility and performance, then buy the other adapters (up to 5 more) to max out your number of monitors.

      Best wishes,
      Bernie

  4. John Trader Reply

    I have a sony viao vpcf127fx it has nvidia geforce video processor, i-7 740QM, 6GB RAM, 64bit Windows 7 Home Premium. I would like to run 2 samsung 25″ 1920 x1200 monitors with the laptop. Use it for trading and charting. Are there going to be any issues, in terms of compatibility and or performance?

    • Bernie Thompson Reply

      The UGA-2K-A will do 1920×1200 natively, so you’ll get the full resolution on those monitors. In terms of processing power, the Core i7 is great. The CPU will not be a bottleneck, although USB is always a bottleneck with two 1920×1200 screens (it will be good for web/apps/stock trading scenario, but you’ll see lag with full screen motion video).

      In terms of compatibilty, you must run the DisplayLink 5.5 M1 driver or later. With that, no compatibility red flags. However, some nVidia/DisplayLink combinations are having trouble right now is with power management – we’ve had intermittent reports of monitors not coming back when the system returns from sleep. A unplug/plug of USB is sometimes required. This is not all systems, and there has been some improvement with the latest DisplayLink 5.6 driver beta.

      Hope these details help. Please visit http://plugable.com/support anytime if you have any trouble. Thanks!
      Bernie

  5. Thomas Darling Reply

    My HP Pavilion Elite HPE-350t with Intel H57 Express Chipset) uses a Radeon HD5450 (1 GB) graphics card.

    Are there any red flags concerning using 2 side-by-side LCD monitors like the HP 2509m with any of your products?

    Which of your products would be applicable to add another monitor to facilitate audio & video editing?

    Tom D.

  6. Lampros Chaidas Reply

    Hi Thomas!

    Your computer’s performance is higher than the DisplayLink recommendations for DVD-video (They recommend a 2GHz Dual Core for the 1280×1024 resolution).

    The HP 2509m however has a native resolution of 1920 x 1080. Running high definition video in that resolution may still be laggy. Also you should avoid the UGA-125 as this won’t go up to 1920×1080 which your monitor needs.

    Your cheaper option (if you don’t care about DVI) is to go with the USB-VGA-165 but it won’t do DVI output, VGA only – it will however do 1920×1080 with no problems.

    Hope this helps!

    Let us know if you have any more questions we can answer!

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