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skypilotpete 0 Newbie Poster

I recently purchased an ATEN KVM CS-72E switch. I am using the switch to connect 2 computers to an LCD monitor.

This setup works most of the time, but sometimes, when I switch to one of the computers, I get the message "Analog Out of Range". This never happened when the monitor was connected directly to the computer (i.e. without the KVM switch) and I have been using this monitor and this computer for a long time.

This is very frustrating as the only way I can get the monitor and computer to recognise each other again is to turn off the computer by pressing the start switch and reboot - losing whatever work I am doing. As soon as I reboot the computer, the switch works correctly and the monitor sees both computers.

The problem only seems to happen when I have been using Computer 1 for a long time without switching back to Computer 2, or when I start computer 2 without viewing it on the monitor. (That is - I start Computer 2 while I am viewing Computer 1, and don't look at it during the startup process). Then, when I eventually switch back to Computer 2, I get the "Analog Out of Range" message. When I view Computer 2 while it is starting up, and switch regularly between computers, the problem does not seem to happen.

I have done a lot of googling and found quite a few "Analog out of range" issues. Interestingly, they all seem to involve LG LCD monitors. However, none of the issues directly match mine and none of the suggestions have been effective.

I have tried contacting LG support and ATEN support, without luck so far.

My setup is:

Computer 1: Pentium 4, 3 gig processor, 2 gig RAM, Windows XP Pro SP2. nVidia Geforce FX 5700. It is on KVM switch 1.

Computer 2: AMD Athlon 1.6gig processor, 1gig RAM, Windows XP Home SP2. nVidia Geforce FX 5200. It is on KVM switch 2. This is the only computer which has shown the problem so far.

Monitor: LG Flatron L1954TQ

I do not have any power saving options activated on my computers. Everything is set to be on all of the time.

Both computers are set at 1280 x 1024 resolution (recommended for the monitor) and at 60 mhz refresh rate. I have also tried them both at 75 mhz.

Both computers have the monitor's drivers installed from the CD that came with it.

I would greatly appreciate some help with this.

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Dani AI

Generated

The pattern described by points to a DDC/EDID handshake problem between the KVM and the graphics card rather than a fault in the monitor itself. When a video card cannot read the monitor EDID it may revert to a default or unusual timing; a KVM that does not preserve or emulate EDID for idle ports lets that happen and the display will report an unsupported signal.

Quick diagnostics (low effort)

  • Reproduce the error and note whether making the problem machine the active, visible input during boot prevents it. If it does, that strongly implicates EDID loss.
  • Swap the video cable and test different KVM ports to rule out a bad cable or port contact.
  • Power-cycle the monitor when the error appears and press the monitor’s auto/auto-adjust control to see if it re-syncs without rebooting the PC.

Practical fixes and long‑term options

  • Use an EDID-saver / EDID-emulator (plugged between monitor and KVM). These devices hold a stable EDID so each PC always sees valid timings even when not selected.
  • Replace the KVM with one that explicitly supports DDC/EDID pass-through or “DDC emulation.”
  • If possible, switch to a digital link (DVI/HDMI) and a KVM that supports digital EDID handling.
  • Look for firmware updates for the KVM and ensure GPU drivers are current; some GPU drivers can be forced to use a persistent display profile or custom EDID.

Cautions

  • Cheap or damaged VGA cables and poor shielding can aggravate sync loss, so use a good, screw-secured cable. If the KVM is under warranty, consider asking the vendor about EDID support or an RMA if behavior is intermittent.
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