IOGEAR 4 Port DVI KVMP Switch with Audio and Cables (GCS1764)

Works great .Fast Shipping. All accessories included. Cons. Vga cards will not work even with adapters.

The short story:
If you just want basic KVM functionality you'll probably be happy. If you want clean sound through it you won't.


The longer, drawn out story...
I've owned a few IOGear KVM switchers in the past and liked them (although I've had to occasionally do a reset on them). This was my first experience with one from them that supports DVI or sound.

I was hopeful that the sound switching would be good after reading a review here on Amazon that said that sound worked perfectly through it. It may be that there's been a redesign since that review since I had the same problem with 2 different samples of the GCS1764.

For basic switching of KVM it works fine. My only complaint with the non-sound functionality is that I don't like the choice they made with the LEDs indicators within the individual switches themselves. They have 2 LEDs per switch to identify what's on and what's active. The upper light is amber and is right in the middle, skinny part of the switch, and it indicates if a PC is turned on (by glowing low) and if it's the active connection (by glowing high). The lower LED is green and is in the lower, fat portion of the switch. It glows high to indicate when the rear USB connections are routed to that connection. To me, what the amber lights are indicating (what PC is active) is more important than what the green ones are indicating (where the rear USB connections are routed), but the amber lights don't do as good a job of it as I would hope. For one thing, our eyes are more sensitive to green light, so if they had just done the colors the other way around it would've been a better choice. In addition, the design of the plastic cover on the individual switches is such that you can't see the amber LED as well as the green LED - the edges of the narrowed part of the switch block about a quarter of the light (there are 2 black lines (from the edge of the plastic cover) going through the LED). So being able to discern the active and passive inputs is compromised a bit by 2 different design choices that I wish they hadn't made. No, it's not horrible, nor is it a deal-breaker for me, but I don't like it. I take off half a star for that.

The other star and a half is because of some sort of design flaw that adds noise to the sound. The nature of the noise is high frequency whines, whistles, and buzzes, with a regular beat to the sound that happens every half a second (2Hz). If my Windows sound settings are at default (all the sliders are at the halfway point) and my speakers are at a low-medium sound level, the noise is audible anywhere in the room, and even discernable out in the hallway outside of our home office.

After experimenting with it quite a bit I figured out that the noise is not added if only a single DVI device is connected to the switch. So, if I have the PC's KVMS outputs connected to the GCS1764, and my speakers (Klipsch) connected to the output from the GCS1764, but the DVI monitor isn't, (and no other PC) then the sound is clean. The moment that I connect either a DVI monitor or another PC's DVI connection the noise jumps into the sound.

It doesn't matter the model of monitor (I tried 3 different models of monitors (all from Dell)), the maker of the video chipset (I tried nVidia and ATI, integrated and PCI Express), or whether the speakers are powered or not (the noise is there in headphones), or whether they're 2 channel or 2.1 channel speakers (for some reason IOGear tech support labeled that as a possible issue). I also tried 3 different kinds of sound cards, add-in (Creative Audigy 2), Creative USB, and integrated Crystal Sound. Even though the noise wasn't a 60Hz hum I checked for ground-loops by plugging all devices into the same power strip (a Trip-Lite that does some waveform filtering). I purchased a 2nd GCS1764 (which I returned) to make sure that I didn't have a bum sample. So I feel that I tested it fairly well.

I contacted IOGear's support when I first noticed the problem and got an email response within a day that was for basic troubleshooting that I'd already gone beyond (e.g. telling me how to reset the unit and that they only support it with powered 2 channel speaker systems (i.e. my 2.1 system isn't supported)). I did what they suggested even though I was 99.9% sure it wouldn't help, which it didn't. Then after I did the more complete testing I wrote an email discussing my findings to their tech support, asking them to escalate the issue to higher-level techs, and let them know that I would be willing to help them troubleshoot the issue further or work with them to help fix the issue, but I never heard back from them (that was about a month ago).

If you have any questions, or want me to try something else, I'll try to check back occasionally in the comments section for this review.

I bought this KVM to support my two monitor setup on 3 different machines. I use it in parallel with a Symphony KVM for the VGA monitors and this on for the DVI monitors. The cabling is a snap and the monitor and keyboard emulation is better than the Symphony. The only thing that would make it better is easier keyboard switching. It would be better if the keyboard and mouse ports were on the back since it would provide a cleaner look.

This product, in conjunction with a pair of DVI EDID identification spoofers, is working GREAT in one of our UAV Ground Station applications.

Excellent High Quality Product - I am proud to be using it... now, if they can come up with a 19" Rack Mount Kit, I'll be completely set.

This switch has been a lifesaver when wanting to share my 24" widescreen monitor with my PC desktop, work laptop and MacBook Pro. I rarely ever have more than one computer on at a time but I have not noticed any problems on the rare occasions when all three are on at the same time. I don't use the audio portion of this switch so I can't comment on that feature but for pure KVM I have no complaints. I was also very impressed that the switch came with all of the cables - a big plus!