DisplayLink’s USB-to-DVI adapter

Last year, Samsung released a 19″ LCD monitor capable of being hooked up via a simple USB connection. To work its magic, the display uses an embedded video chip made by a company called DisplayLink that works like a sort of self-contained graphics processor. That’s neat, but what if you already have a spare monitor you’d like to use via USB? Is there a cheaper alternative to coughing up the $300 or so for a USB display? As it turns out, yes there is. DisplayLink’s video chip is also available in standalone USB-to-DVI adapters, which allow one to connect any monitor with a resolution up to 1600 x 1200 via USB.

The prospect connecting pretty much any display without an extra monitor port has obvious appeal, especially for laptops. USB only has a fraction of the bandwidth supported by the DVI interface, but DisplayLink nonetheless claims on its website that it’s fast enough to allow “flawless DVD playback” and to enhance one’s gaming experience in “most games.” I was curious to put these claims to the test, so I got in touch with DisplayLink and the company graciously offered to send me a sample USB-to-DVI adapter.

DisplayLink’s USB-to-DVI adapter.

You won’t find this exact device anywhere commercially. Instead, you’ll need to look for an adapter built by one of DisplayLink’s partners, such as this Sewell model that’s available for $149.95. The drivers are the same, though, as should the hardware be in both adapters.

Trying the adapter in Windows XP

Since the usefulness of DisplayLink’s adapter ought to be greatest to laptop users, I first tried it on my now-aging IBM ThinkPad T41 (yes, it’s so old it’s not Lenovo-branded). The machine has Windows XP Professional installed, and it includes a modest 1.7GHz Intel Pentium M processor coupled with a Mobility Radeon 9000 graphics processor and 512MB of RAM. Getting the adapter to work on this system was a breeze. I ran the installer, rebooted, and was good to go.

I tried three different LCD monitors—a 20.1″ ViewSonic wide-screen display, a 19″ LG wide-screen display, and a standard 17″ LG—and they all worked flawlessly as soon as I connected them, just like they would through a DVI or VGA connection. DisplayLink allows you to configure multi-monitor settings right from Windows’ built-in display control panel, although the company’s own tray application provides a quicker way to change some of the same parameters, like the extra display’s resolution and behavior. Everyday desktop tasks behaved smoothly, so I tried to pop in my Raiders of the Lost Ark DVD to test full-screen movie playback. The DVD played smoothly on the 17″ display at 1280 x 1024, but playback on the 20.1″ pegged my laptop’s CPU to 100% and caused dropped frames. Normally, CPU utilization while playing a DVD on the machine’s 1440 x 1050 display is quite low, so there’s evidently some overhead involved with the DisplayLink adapter.

Moving to Windows Vista

Now excited to try DisplayLink’s claim about gaming on a worthy machine, I installed the adapter on my main desktop PC, which runs Windows Vista Home Premium and in whose entrails tick a Core 2 Duo E6400 processor, a GeForce 7900 GTO graphics card, and 2GB of DDR2-667 RAM. Unfortunately, this step is where the magic wore off. DisplayLink’s drivers installed and behaved as diligently on Vista as they did on XP, but performance was noticeably worse right off the bat—even on the 17″ display. Windows moved choppily, scrolling in Firefox on any site with flash ads caused very noticeable slowdowns, and all videos dropped frames. Turning off Vista’s Aero graphical interface helped performance, but it caused Windows Media Player to fail to render anything on the DisplayLink device. VideoLAN and Media Player Classic weren’t any help, either.

DisplayLink’s adapter driving my ViewSonic VX2025wm in Vista. The other display is connected via DVI.

I was still determined to at least try gaming, so I kicked off a game of Team Fortress 2. As expected, the game was unplayable even with the resolution turned down and Aero disabled. Puzzled by this mediocre display performance, I dropped DisplayLink a line to ask if what I was experiencing was normal. After a few days, the company’s PR representative got back to me with the following information:

– DisplayLink performance in gaming environments is much better in resolutions less than 1024 x 768. This will be improving in the spring timeframe with the next major update to the software.

– The primary focus of the technology until now is office applications. Your readers should know that this is not yet optimized for gaming apps, but that the company is working on that. The most appropriate use – for now – is chat screens or strategy screens.

So much for enhancing your gaming experience. The next morning, I was awakened by a phone call from one of DisplayLink’s UK-based staffers, who quickly informed me that my GeForce 7900 GTO graphics card was to blame for the issues I had encountered. GeForce 7900- and 7300-series models suffer from a “CPU copy bug,” he said, and other GPUs should perform “ten times faster.” However, he went on to say that even moving windows around in Vista is supposed to be “generally a little slower” than in XP. After probing around a little more, I got the impression that Vista performance is still very much a work in progress. I wanted to give DisplayLink the benefit of the doubt, though, so I took out my 7900 GTO and popped in my old GeForce 6800 GS in order to give the adapter another go.

Despite DisplayLink’s assurances, performance with the 6800 GS was very similar to what I had witnessed on the 7900 GTO. Moving windows around was admittedly a little smoother, and videos dropped fewer frames, but there was still noticeable choppiness everywhere. Even scrolling TR’s front page was slow and sent my CPU usage through the roof. Someone using the adapter to do office work on a 17″ or 19″ display probably wouldn’t notice those types of slowdowns too much, but anyone else most likely would.

Conclusion

Overall, DisplayLink’s USB-to-DVI adapter is a mixed blessing. On one hand, the device has undeniable potential, and it works fine in Windows XP provided your monitor’s resolution isn’t too high. On the other hand, its poor performance in Vista is a pretty big caveat and could seriously impede its usefulness on most newer PCs. DisplayLink’s spring release time frame for its driver update means a speedier driver may not be available until June, which is a pretty long time to wait.

I would be more inclined to forgive poor Vista performance if this were February 2007. However, Vista has been shipping on most new PCs for over a year now, and the release-to-manufacturing version became available all the way back in November 2006. DisplayLink may have limited resources to spend on driver development, and the limitations of the USB interface could be more to blame than lackluster drivers, but incomplete Vista support today is nonetheless hard to swallow—especially for a product with a $150 price tag.

Folks seriously considering this adapter will need to evaluate carefully whether their hardware, operating system, and usage patterns are suited to it—and whether tossing in a cheaper PCI or PCIe x1 video card might not be a simpler alternative. If you’re a laptop user who still runs Windows XP, or if you have a Vista laptop and only need an extra display for office work, then the adapter is a decent choice. However, there are compromises in both cases, and DisplayLink’s product really can’t be considered a full-featured replacement for a proper DVI output—at least not yet.

Comments closed
    • Usacomp2k3
    • 12 years ago

    This would potentially be very useful in a server environment, I would think.

    • evermore
    • 12 years ago

    I just noticed the horrendously long USB cable they include. How long is that thing, 6 feet? Then you’ve got the usual 6 feet of a DVI cable to throw in, or at least a 3 foot cable, so you’ve got all this cable hanging off a USB port from your laptop or coiled up near your desktop. I guess USB cabling is cheap so they just threw in enough to look impressive.

    • newbie_of_jan0502
    • 12 years ago

    This would be perfect at work. We use Matrox f1400 (fiber connected remote graphic units) which makes a keyboard worthless until the drivers are running. This would solve a lot of headaches.

    • rythex
    • 12 years ago

    seriously, what is the point of this thing? incase you REALLY need a second monitor on some PC that doesn’t have a spare PCI or PCI Express slot to put a cheap ass video card in? what a niche product.

      • ludi
      • 12 years ago

      You may have noticed that laptops — particularly cheap ones with limited ports and video chipsets — are increasingly dominating PC sales these days?

    • Hattig
    • 12 years ago

    Well, it’s one way to get a DVI output from the myriad of PC laptops with VGA connectors on them *still*. It’s a nice idea, and great for multiscreen setups in the office.

    I imagine that the graphics setup is highly configurable. It might even be possible to add graphical output to a device with USB output only (all those wireless routers with USB, anyone?), with a software driven framebuffer internally. Of course, this is worthless when the device costs so much currently. Get it down to $50 and then we’re talking.

    • BobbinThreadbare
    • 12 years ago

    You know, seeing this device makes me want external PCIe become a reality very quickly. I can only imagine the innovation we will see.

      • SuperSpy
      • 12 years ago

      Or, perhaps, eSATA.

      • indeego
      • 12 years ago

      Innovation like whatg{

    • evermore
    • 12 years ago

    You couldn’t find a decent-powered XP desktop to test it on? Makes the review somewhat incomplete to only test it on an operating system for which it’s obviously not optimized. Testing XP on the laptop is one thing, but for comparison purposes it’d be nice to see how it does in XP with more powerful hardware. (And XP isn’t going away anytime soon. I’ve tried using Vista on my new laptop and I really just don’t like it, even when I switch it to “Classic” theme.)

    They’re on the verge of fraudulent advertising if they’re claiming this will be great for gaming. I suppose technically “most” games, meaning the majority, don’t need high resolution or 3D hardware acceleration, but that’s because there are vast numbers of churned-out clones and puzzle games that sell for 5 dollars as bargain games in nothing but a jewel case. No gamer’s game made in the last 5+ years looks good under 1024×768, and that’s still a bare minimum.

    If office applications run okay on the thing, then that’d make it nice for some uses, obviously particularly if you need to swap displays between machines.

    There have been devices like this on the market for along time, incidentally, although this is the first I’ve seen with DVI instead of VGA. At the resolutions this can really handle though, that makes no difference.

      • Usacomp2k3
      • 12 years ago

      Vista’s the present and the future. A device like this isn’t a stopgap, so why would you want to test it extensively on a platform that has a short life left?

        • albundy
        • 12 years ago

        cus it cant perform under a bloated OS? just a guess…

        question is, do you really use windows, or the applications that you install on it?

          • Usacomp2k3
          • 12 years ago

          Right. I take it you don’t use Vista as your primary computer?

    • Dachande663
    • 12 years ago

    Surely it would just be cheaper to use one of Matrox’s Dual Head2Go (or even the triple head)?

    • UberGerbil
    • 12 years ago

    So, I’m confused about how this claims to work (and their site doesn’t help). It /[

      • Damage
      • 12 years ago

      As I understand it (from when I spoke with them at IDF), they are using the CPU to compress the images in real time. A faster CPU will help performance to some degree, as will multiple cores. However, there are limits on the compression’s effectiveness and USB’s data rate. Cyril’s nice Core 2 Duo desktop still struggled, probably due to these other constraints.

      • Cyril
      • 12 years ago

      To add to Scott’s reply:

      q[

      • zqw
      • 12 years ago

      Readbacks from the GPU cause pipeline stalls, so 3D games are unlikely to ever work well, along with Vista Aero.

    • Prototyped
    • 12 years ago

    w00t, I think I spot an IBM Model M keyboard.

    • pikaporeon
    • 12 years ago

    Looks like a good pickup for EEEXP users… which brings the next obligitory question

    will it run (on) linux?

      • Mithent
      • 12 years ago

      §[<http://sewelldirect.com/USB-to-DVI-External-Video-Card-High-Resolution.asp<]§ Well, Sewell only say "The USB to DVI/VGA card is completely Windows Vista compatible with the included driver CD for both mirroring and extending your desktop. It performs both mirroring and extended desktop with Windows 2000 SP4, and XP SP2 perfectly (32-bit systems only)." No mention of a Linux driver, and one would obviously be required.

    • Cova
    • 12 years ago

    Sounds like a great way to add more screen real-estate for office use – I’ve already got 2 LCD’s on my desk, and it isn’t really that easy to add a third, until this. Knowing if it has any linux support at all would be nice to know though.

      • Usacomp2k3
      • 12 years ago

      A 7300 doesn’t fit in your computer?

    • Kurotetsu
    • 12 years ago

    This strikes me as having the same problem inherent to USB speakers, which bypass any discrete sound card acceleration you might have. I suspect the subpar performance in anything other than general office use might be due to the USB link bypassing the video card (and any hardware acceleration you get out of it) altogether?

    • bthylafh
    • 12 years ago

    Could it be that your desktop PC has a crappy USB adapter? Something like this will surely stress a USB controller, and since those things rely on the CPU…

    If only Firewire had become more popular.

      • TechNut
      • 12 years ago

      Agreed. USB is host CPU dependent for processing interrupts and data off the port. Many motherboards also share physical IRQ’s based on the slots or other peripherals with the USB controller. i.e. a network adapter and the USB hub on the same IRQ, or even worse, a hard drive controller interrupt with the USB port.. Amazing 1980’s PC architecture at work here. ACPI does create virtual interrupts (which allows Windows and Linux to assign more IRQs so there are no internal conflicts), but, they are still physically tied to 16 IRQ’s on the motherboard itself. I still set my IRQ resources manually on PC-class motherboards.

      I’d suggest opening up the motherboard manual and see what peripherals are sharing the IRQ with the USB port. I’d move the IRQ around if possible. I’ve seen that cure many USB problems.

      Anything that reduces the number of interupts the CPU has to service, especially ones shared with the USB port will help the performance. Most people do not notice because USB is not super fast. This is also one of the reasons why USB speakers pop and crackle.

        • evermore
        • 12 years ago

        ACPI has nothing to do with IRQs. Advanced Programmable Interrupt Controller (APIC) is present in newer systems which allows up to 24 IRQs commonly, but up to 255 technically. These are not “virtual” IRQs, they’re real hardware IRQs. IRQ sharing is also mature and functions quite well in the majority of systems. The IRQ routing table in the BIOS and in the operating system maintains a “link value” for each device which is associated with the IRQ, so every device in the system could technically use the same IRQ; it just does a lookup, similar to network address translation used in most broadband routers.

        There are of course buggy implementations that can cause issues but I have yet to encounter any problems with IRQ sharing. Right now I have 5 devices sharing IRQ 16: P35 PCIe root port, ICH9 PCIe root port, USB controller, JMicron IDE controller, and Geforce 7600GT. Four devices share IRQ 17, 3 share IRQ 18, 2 share IRQ 19. The system has skipped over the lower IRQs commonly used for things like IDE controllers, serial and parallel ports, things that the P35 chipset doesn’t support, which is nice since it just avoids any possible conflicts.

    • derFunkenstein
    • 12 years ago

    Maybe they’re just having problems working with nVidia GPUs in general. Do you have an ATI one laying around anywhere? Of course, if DVD playback on a Radeon 9000 had dropped frames, I’m sure Vista gaming won’t be much better.

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