Introducing the Gefen DVI DL

Fairly well-known in the home theater community for their HDMI switch boxes, Gefen was the logical choice for finding a dual link DVI KVM. The benefit of a DVI based KVM is that a lot of the issues that plagued old analog VGA KVMs are no longer a problem, thanks to the fact that DVI-I signals are transmitted in the digital domain, meaning that the signal that leaves your computer is exactly what gets displayed on your monitor. With analog VGA based KVMs, you often had image quality degradation at higher resolutions, especially if you happened to have a lower quality KVM. So, in theory, thanks to an all-digital connection, we should have no problems with just about any DVI based KVM switch. Our confidence in the DVI specification aside, we had heard very good things about Gefen, once again from the home theater community - and if anyone has a very critical eye when it comes to image quality, it is the home theater community.

Priced at $399, the Gefen DVI DL is not cheap, but neither is the monitor you'd be hooking this up to, so although we don't agree with the price premium, this product isn't exactly targeted at the low end of the market. So, after you're done buying your $600 video card and $2500 monitor, what's another $400 for the DVI DL?

The Gefen DVI DL is a fairly simple device that acts as an electrical switcher between two computers. The DVI DL will switch between two dual link DVI inputs, analog audio as well as USB 2.0. It is important to note that the DVI DL does not provide USB or DVI "emulation"; in other words, when you switch between systems, it is akin to unplugging the USB and DVI cables from one system and plugging them into the other - that's exactly what the OS "sees" when you switch using the DVI DL. Some units do provide USB emulation, but we'll address this topic later on as we talk about our experiences with the DVI DL.

The unit itself isn't incredibly stylish, but it is functional. At the front, you have a power LED, IR receiver for remote control switching, a pair of indicator LEDs that tell you which system you're switched to, a select button and two EQ adjustments. The EQ adjustments are to fine tune the DVI signal to compensate for sending it over longer than normal cable lengths. Each system gets their own EQ knob, which can only be adjusted with a very small phillips or flat head screw driver.

On the rear of the unit, you have three DVI ports, four USB ports (2 type A and 2 type B), and three 1/8" audio ports. There is also a connector for the AC adapter on the rear of the unit.

Gefen ships the unit with an IR remote control. The remote works very well from fairly long distances, but as with all IR devices, you need to have line of sight to the unit in order for the remote's commands to register. The remote is powered off of a single 3V CR2032 watch battery, and Gefen is kind enough to supply you with two batteries when you order the unit. Unfortunately, while you do get a remote control, the DVI DL does not support any keystroke combination switching, which is a fairly large downside in our opinion.

Unlike most KVMs, the DVI DL comes complete with all of the cables that you'll need to get it up and running. You get two DVI cables, two USB cables and two 1/8" audio cables. For whatever reason, the DVI and USB cables are in Gefen's unusual blue color, which tends to not match anything, so you may want to keep your cables hidden if you are trying to put together that oh-so-stylish Apple workspace.

The setup is fairly simple, but it can be confusing if you don't think of the inputs and outputs from the perspective of the switch box. It's pretty easy to guess which one of the three DVI ports goes to your monitor; it is the one labeled "DVI Out". The DVI 1 and DVI 2 ports connect to the DVI outputs on the two systems that you are going to be switching between. The same applies to Audio 1 and Audio 2, with Audio Out going to your speakers.

The only somewhat confusing aspect of the setup deals with USB setup. The two type A ports are labeled USB Out, and this is where you plug in the USB devices that you wish to switch between computers (e.g. keyboard, mouse, etc.). You can even plug in a USB hub to these ports if you'd like (more on that later). The two type B ports are for connecting to your computers: In 1 goes to the first computer and In 2 goes to the second. Obviously, it's very important that DVI 1, In 1 and Audio 1 all go to the first computer, and all of the ports marked "2" connect to the second computer. Otherwise, you'll only be switching some of the components to the right system when you go to hit the select button.

Index DVI-DL Operation and Issues
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  • Tutor - Sunday, October 30, 2005 - link

    Dr. Bott has great KVMs. I use a VGA with USB switcher and it is great. Did not have the opportunity to test their DVI product, but maybe Anand will ;-)
    It is not dual link, but rated for 1920 * 1200. German web site states a dual link device will be available in the future.

    http://www.drbott.com/prod/db.lasso?cat=moniswitch">http://www.drbott.com/prod/db.lasso?cat=moniswitch
    Reply
  • kencl - Monday, October 24, 2005 - link

    Just thought I'd pass along http://www.kavoom.biz/">another software solution. It's M$ Windows only unfortunately, but that may be exactly what some of you are needing (not me, unfortunately, I need to switch into a Linux system - maybe there's an Win32 X-Windows client out there somewhere....) Reply
  • supaxi - Saturday, October 22, 2005 - link

    I know this is a bit out of left field, but I wanted to mention a software KVM program that I use a lot. It lets you use one mouse and keyboard with any number of systems. I use three computers at work and this is real life saver as I hate KVM switches. You can try it at http://www.neslosoftware.com">http://www.neslosoftware.com

    They don't support unix but I'm sure you could find a similar program out there someplace.
    Reply
  • tortoisehead - Thursday, October 20, 2005 - link

    I bought a gefen switcher a few weeks ago because remote logins don't cut it for video or gaming, and I was sick of switching the usb and dvi cables between my pc and mac. I have the "2x1 DVI KVM" and have had several issues like the ones the reviewers came across. In case there are other gefen owners reading this article, here's some info on how I got my setup to be stable.

    I went through hell just trying to to get the ability to switch back and forth between my PC and Mac without praying that it would work correctly. You wouldn't think a switcher would be that hard, but like others have said no one can seem to get it right. I had crashes, devices not being recognized correctly, and the monitor not turning on when I switched. Sometimes repeatable, sometimes not. That can be so frustrating.

    In the end I replaced the DVI cable going to my Mac with one I got from work (from Dell). That ended the dock crashing every time I switched back to my Mac. Who knows what is wrong with the cable that gefen gave me. I asked in their forums, and they recommended to pull out one of the DVI pins! Too bad after I did that the cable didn't work at all anymore.

    As far as the PC, I had two wireless logitech controllers that were apparently causing issues with the switcher and XP. One for the keyboard, and one for the mouse. Once I set it up to communicate with both devices using the keyboard controller, I removed the mouse-only controller and had no more usb problems.

    One of the most frustrating things I ran into was the same thing documented in the review. You bring up any problems in the gefen forum and the first thing they tell you is to buy their $80 "DVI Detective" to fix their own buggy hardware! That's just lame, especially with the price of DVI switchers. And if Macs have problems with DVI cables having certain pins, why not have the option of one of your DVI cables being a "Mac" version when you buy the switcher?

    So long story short, I can't really recommend gefen's products either. Please chime in if you have had a great experience with an affordable DVI switcher!
    Reply
  • Scorpion - Thursday, October 20, 2005 - link

    Wow I'm so happy to see a KVM article! I still use my old Hawking 4-Port KVM. I've been trying to upgrade to a newer KVM with DVI and USB support for mouse and keyboard, but I just can't find any! I was even at a Fry's (out of town, there isn't one where I live) and I looked at this huge Isle of KVMs, and I could maybe find ONE that supported DVI or USB, but never both, and the ones I found just didn't have the functional look I wanted. Where is this market? I know several people with multiple computers and limited desktop real-estate for multiple monitors, keyboards, and mice. KVMs are great for this situation, there just aren't enough people who do it right.

    I'm really looking for a good KVM DVI+USB, not to be used with any wireless keyboard or mouse. If anyone has any recommendations I'd greatly appreciate it. It's good to see some attention pointed towards this market segment.
    Reply
  • Nocturnal - Wednesday, October 19, 2005 - link

    I wonder if more sites did more reviews on KVMs that they'd kinda get to work on fixes for the flaws that the reviewers find. I want the IOGear GCS1774 but it does not work with any nVidia 3/4 chipset which is very bad. Reply
  • ky - Wednesday, October 19, 2005 - link

    How do you get a 30" for $2500?

    Pixar and Apple employees get a standard discount of 15% before tax so that comes pretty close to $2500 ($2549). Maybe reviewers get > 15% off? Or another reason might be due to cash back discounts or site referrals (fatwallet) you might bring it closer to $2500.

    Why buy a $400 switcher when a 2nd 20" display is only $400?

    I dunno about you but if both my computers can power the 30" in all its magnificence, I'd rather use the 2nd computer w/ the 30" than a piddly 20". OTOH, w/ a 2nd monitor, you can use both at the same time rather than alternatively. It's just a preference thing, I guess.

    Gefen has has a long history of "screwing" their customers with their suggestions (read: upselling) of buying additional products to solve problems with products you've already purchased. Back when I was using the 23" display, they suggested I buy a 2nd identical product to troubleshoot my existing ADC Switcher w/o any mention of sending one back or for credit. Even the CS rep remarked that I probably didn't want to do it but it was a suggestion. Don't hold your breath on the integration of Auto-EQ or DVI Detective into the next version of the DL KVM, they've said things in the past about previous products having problems and perhaps addressing them in a future version of the product but they never followed through.
    Reply
  • n7 - Wednesday, October 19, 2005 - link

    Remind me to never ever purchase a Gefen product.

    Any company that has the nerve to suggest i buy another product to make their own defective product work properly can go DIAF, to put it nicely, LOL.
    Reply
  • Aquila76 - Wednesday, October 19, 2005 - link

    Try finding a KVM (DVI or not) that works with a USB cordless keyboard & mouse. I tried a Belkin, Tripp-Lite, and IOGear; all would lose or mess up the tracking for both the K & M when I switched away to my other box.
    I have a Logitech Cordless Elite Duo, it has one USB plug that goes to the receiver for the K & M. I think that is what's screwing the KVM switches I've tried, as they apparently need seperate plugs for both.
    Reply
  • johnsonx - Wednesday, October 19, 2005 - link

    I think your issue is that when you switch your USB device looses power for a moment... that's enough to kill the wireless receiver and make it loose track of the kb and mouse.
    Reply

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