I recently bought a very sleek widescreen LCD computer monitor and used it to replace two CRT monitors that made a marginal widescreen display. The problem was that I have two computers on this desk (a tower and a laptop) and both need to share the monitor. I needed the computer version of a menage a trois, and everything had to play nice together.
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The solution was a KVM (Keyboard-Video-Mouse) switch, which lets you use one mouse and one keyboard on multiple computers. Since I had a USB mouse and keyboard, I wanted a USB KVM switch -- for which I quickly found the choices were limited. I searched for a while and settled on the iogear GCS632U, a two-port USB KVM switch.
What It Is
The iogear GCS632U is a small gray-and-white plastic box about the size of a pack of cigarettes. It has two heavy cables radiating from it, one for each computer. On the front face of the unit are USB connectors for a mouse and keyboard, and a standard 15-pin VGA connector. On the right side is a mini stereo connector for audio output.
Each of the heavy cables run to the computers that you want to control using the GCS632U. At the computer end, the cable breaks out to a 15-pin VGA connector, a USB connector and a standard male mini stereo connector. The VGA connector attaches to the VGA port on the computer, the USB connector plugs into any USB port and the mini stereo connector plugs into the computer's audio output jack. It's not hard at all to connect and it's interesting to point out that the keyboard and mouse signals are carried on a single USB cable.
Note that the GCS632U has only VGA connectors for computer display and it does not handle DVI signals. Since my laptop has only a VGA connector, this was fine for my setup. However, I much prefer to use DVI whenever possible, as it's my experience that DVI makes a much better image than VGA. I'll come back to this point a little later.
The iogear GCS632U switches between computers with two quick presses of the "Scroll Lock" key on the keyboard. There are two lights on top of the unit to show which computer is the one currently connected. The maximum display resolution that the GCS632U will pass is 2048 x 1536 pixels, which seemed comfortably high for my application. The unit requires no power, as it draws power from the USB ports of the connected computers.
The iogear GCS632U came only with the unit itself, its attached cables and a thin manual. You can operate the GCS632U with only one computer on at a time and it's perfectly happy with both computers on as well.
Hooking It Up
The heavy cables running from the GCS632U are about four feet long. Since my laptop is at the far left on my desk and the tower computer is on the floor at the far right, the cables were just barely long enough to reach. As luck would have it, the laptop's VGA port was on the side farthest away from the GCS632U but everything did reach, if barely.
The VGA connector on the front of the GCS632U connects to a cable running to the monitor and the audio connector on the side of the KVM switch feeds audio to my audio monitors. In this case, I am using the speakers in the LCD monitor.
Hooking this up took no more than 10 minutes and it was particularly nice to not deal with a power supply. I already have far too many cables snaking around, so one less is a good thing.
How It Works
I switched my computers on one at a time and it took a couple moments for each computer to recognize the GCS632U and do all the necessary handshaking. (Both computers run Windows XP SP2.) No drivers were needed and no driver disk was supplied. Once set up, the GCS632U switched exactly as described -- two quick strokes of the Scroll Lock key switched the display, keyboard, mouse and audio from one computer to the other. It's cool when a piece of technology like this works perfectly out of the box.
After a couple weeks of use, I have found no glitches in the operation of the mouse, keyboard or audio through the GCS632U. All keys on the keyboard do exactly what they're supposed to do and the mouse switching is perfect. When one computer is connected, the other one just sits there idling in exactly the same spot I left it. In addition, the audio switching is perfect, as far as I have yet tested. Other reviewers commented that the frequency response of audio through the GCS632U is tinny but I've not really noticed that. On the other hand, I have the unit feeding the tiny speakers in my LCD monitor and there is no subwoofer. I plan to add a subwoofer and that may change my opinion of the audio path through the GCS632U, but it's fine so far.
My new widescreen LCD monitor has a resolution of 1680 x 1050 pixels and my initial impression was that the VGA image quality through the GCS632U looked good, too. However, the closer I looked, the more I could see slight ghosting in the VGA image. Where something had a strong vertical line, there would be a faint ghost just to the right of that line. It was very faint but I'm a video engineer and know that even faint ghosts degrade apparent resolution significantly. The average viewer might not notice and it wouldn't affect applications like word processing or spreadsheet work, but we use this monitor for graphics composition and digital photography -- I wanted every pixel of resolution.
Therefore, I removed the VGA switching from the GCS632U and I use it only for switching the keyboard, mouse and audio. I take a VGA signal from the laptop and feed it directly into the LCD monitor's VGA port, and take the DVI signal from the tower computer and feed it directly to the monitor's DVI port. This gives me the best possible image quality and there is no hint of ghosting when the cables are directly connected to their respective computers. Clearly the ghosting comes from the VGA switching circuit inside the GCS632U.
Again, I want to state that this ghosting is very faint and that I'm operating at a fairly high resolution (1680 x 1050). Most people would probably not see the ghosting, or if they did notice there was something slightly off, they wouldn't be able to articulate exactly what it was. And there's a very good chance that lower resolutions would show less of this minor artifact. However, I had a simple workaround to give me the best possible quality, so I took it.
There is no apparent loss of image brightness for VGA signals passing through the GCS632U. In other words, my display looks just as bright and contrasty connected through the GCS632U as it looks connected directly to the computer.
Despite the long-winded discussion above of image quality through the iogear GCS632U, I like this unit. As far as switching the keyboard, mouse and audio is concerned, it works perfectly and glitch-free. It is small, consumes little space, is easy to connect, requires no drivers and does not use an external power supply. Yes, the VGA signal through it is slightly flawed but this will not be noticed by many people and it will not affect use of many applications. You should only be concerned about it if you plan to do a lot of graphical work or other operations where image quality is paramount. Switching between two computers that control engineering operations will not be a problem at all.
Since I have a simple workaround for the image issue -- and this workaround lets me get superb DVI image quality from my tower computer -- I'm actually happy it worked out this way. I'm not at all disappointed that the image quality through the GCS632U is a notch below perfect. And the keyboard, mouse and audio switching have been perfect.
However, I can't get to five stars for the iogear GCS632U, since there is that pesky lack of perfection in the VGA signal quality. I do like the unit though, and think it is a four-star (out of five) product. With the mild warning that VGA signal quality through the GCS632U is slightly degraded, the unit is otherwise a fine product.
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Amount Paid (US$): 50
Driver Availability: Windows, Linux, and Mac