Kvm Switch and Kvm Cable 101

KVM Switch and KVM Cable 101

There are a wide variety of KVM switches that meet a wide range of needs, from complex switches that allow you to control 16 or more computers in server rooms to simple ones that control two computers in home networks. Of course, prices vary as well, from thousands of dollars to $50 or less.

Despite the differences, all KVM switches share the same basic concepts. As we mentioned earlier, you connect a keyboard, video monitor and mouse to the KVM, and then use KVM cables to connect each computer to be controlled to the KVM switch. You use some method to switch between the computers being controlled, switching from computer to computer...using a single keyboard, monitor and mouse.

Here are some things to keep in mind as you decide which KVM switch might be right for you:

Decide how many computers you'll want to control. Many computer users may want to pick an inexpensive model that will control only two computers, a so-called 2-port KVM model. However, as soon as they decide to add a third computer, the 2-port KVM switch becomes worthless and they'll have to replace it with a 4-port KVM or even 8-port KVM model. We suggest home users consider a 4-port model to control two computers with room to grow for an added laptop or other computer.
Control method. Some models allow you to control the KVM switch from the keyboard using "hot key" commands, a combination of keys pressed at the same time or in sequence. Others, provide simple push buttons on the switch itself to change the computer being controlled. Still others provide both types of control methods.
Display. Likewise there are different methods to display which computer is currently being controlled. Inexpensive models will have a simple LED on the KVM switch to indicate which computer is currently being controlled. More expensive models have on-screen displays that will indicate the computer being controlled directly on the monitor.
Resolution. One of the key things to look for when purchasing a KVM switch is the resolution capability. Many computer users have graphics cards and monitors that will display very high resolutions and very high frequencies. Resolution relates to how precise the image is (indicated by pixels or dots per inch) and common resolutions are 1024x768, 1280x1024 or even higher. Frequency relates to how often the screen is drawn and frequencies below 60 Hertz can result in screen flicker on regular computer monitors. Since the video signal must pass through KVM switches, they differ in their ability to handle the resolutions and frequencies. Thus, the image shown on the monitor can actually be degraded by the KVM switch. The key is to look at the specifications for KVM switches and make sure that the models being considered can handle at least the resolution and frequency currently being used. Even higher is better since it gives "head room" for the future.
Cables. All KVM switches use special KVM cables, but some are more custom than others. Some other models use cables that are "universal" KVM cables and will work with several makes and models of KVM switches.
Ports. Closely related to cables are the types of ports that the KVM switch uses. Today, most switches use PS/2 connectors for the keyboard and mouse, but you can still find some that have the old, larger keyboard connector (or include adapters) and serial ports for old-style mice.

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