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Choosing Your KVM

The first step in choosing a KVM is to figure out how many computers you’ll be connecting. Two? Three? Four?

Next, determine/decide basic details of what you’ll be connecting:

  • Which mouse and keyboard do you plan to connect? Do they have PS2 or USB connectors (or both)?
  • What kind of ports do your computers have for the mouse and keyboard—USB, PS2, or both?
  • Do you want to also switch speakers/headphones and microphone?
  • Form factor (shape) of the KVM. You wouldn’t think this would make a big difference, but it may. Belkin’s four-port OmniView, for example, stands up and looks nifty...until you plug in the cables, at which point the design suddenly makes a lot less sense.
  • Which platforms (operating systems), and which versions of those platforms are you using—Windows, Mac OS, Linux/UNIX, Solaris?
  • Display device(s)—CRT, LCD, etc. and resolution(s). Will you be doing any gaming or other high-resolution applications, possibly higher than the KVM supports?
  • Doing any time-critical activity? Some KVMs may need a second or two to reestablish the mouse or keyboard connection. The KVM I’m using seems to episodically "lose" the keyboard connection when I switch, until I jiggle the cable.
  • How many mouse buttons do you plan to use? KVM Switches Online’s FAQ notes, "KVM manufacturers will only support up to a three-button mouse. Different peripheral manufacturers do things differently and therefore they have not created a standard to work with. It is possible your mouse will work but [neither] the manufacturers nor KVM Switches Online can say that it will work."
  • Do you have any wireless peripherals? Some may work, but don’t assume that they will. IOGEAR says theirs will work, for example. Some vendors may include learning remotes that interface. Be sure to check with both the peripheral vendor and the KVM vendor for compatibility lists before you buy.
  • Are there USB peripherals you’d like to have connected to the active system, but not automatically—printer, burner, external drive, USB headset? Remember to check for independent peripheral sharing.

Where will you put the KVM switch? Someplace convenient, presumably—although if the KVM you choose supports hot keys, you may be able to do switching from your keyboard. How far apart will the computers be? This measurement may influence your cable choices in terms of length—or rule out some with too-short built-in cables. Cables can easily double the price of your KVM purchase. According to KVM Switches Online’s FAQ:

Why are some of the cables so expensive? KVM cables are heavier than most computer cables; they are shielded and allow for better transmission of the signal. Some manufacturers also decide to use proprietary cabling for their switches. This allows them to eliminate one source of error when troubleshooting. Since all switches are different, it’s hard to know how a generic KVM cable will work with every switch. When a KVM switch has a lot of ports, it is also to use cables with special connectors to eliminate a cabling nightmare on the KVM switch.

Some KVMs use standard cables; others use proprietary cables. You can also find KVM extender cables in many computer stores, in case you guessed wrong. Depending on your current equipment, you may also need one or more "gender-mender" or type adapters to plug things in. The allotted space in the back of the KVM may not have enough room for your current cable terminators. For their four-port USB/PS2 OmniView, Belkin thoughtfully included two short extender cables—helpful in jiggering my keyboard and trackball connections into place. For my old rotary switch, I ended up needing a bunch of male-to-male video adapters, along with sundry keyboard and mouse cable adapters, going to older computers.

Next, reassess your AC outlet situation. A KVM shouldn’t need any great amount of power, but you may need to plug it in. If you’re now having more computers plugged in concurrently, do you have enough outlets in your UPS on the "backup power" side?

Does the KVM you’re considering require external power? Some will take power from the computer; others offer an optional AC power supply. If the KVM includes a USB 2.0 hub, check whether these are (or can be) "powered ports," and if so, whether you need an AC power supply.

Now it’s time to select a KVM reflecting your systems and constraints.

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