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I have a perplexing situation I've not found an answer to. Here is my setup. I have two computers attached to a ConnectPro DVI KVM switch. One computer has an ATI Radeon 5750 Windows 7-64bit) and the other has a NVidia GeForce 8400GS (dual-boot-XP and W7). I am not having an issue with the ATI card. The NVidia card comes up properly when booting up in either OS and when I switch to the ATI computer it works fine. The problem is when I switch back to the NVidia computer there is no video. I've installed the latest drivers in both OSs and even tried rolling back to older versions. No change. With no drivers installed in the OSs it works properly but this is no solution. Has anyone else run into a similar situation?

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I have the same card on a linux box attached to an avocent kvm over vga. I had no problems with it.

Moreover, can i ask what do you mean with "with no drivers installed"? Windows 7 tends to automatically install his nvidia drivers, if nothing else is available. To remove them you have to explicitly go to device manager and uninstall the drivers. Is this what you did? or no drivers = windows 7 stock nvidia drivers?

In any case, what you could try to narrow down the problem further is

  • try with a ubuntu live usb/cd, and see if the problem persists (it should use nvidia drivers, afaik)

  • try a different kvm, if you can

  • make sure it's not the monitor that tries to feed from the wrong input

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On the channel of your NVidia GeForce 8400GS (dual-boot-XP and W7)system connected, you can turn the optional setup of the channel called "DVI Re-Trigger" On.

To turn the "DVI Re-Trigger ON", hold down the push button of the channel and until you hear a serial of beep sounds. Three beeps means "Off" and two beeps means "ON. You can turn it on/off alternatively. Once you turn it on or off, the switch will remember the setup.

The reason for this option is because there are countless operation systems in the market. Some of them have different procedures for checking DVI connections. For example, if the user has Windows XP with a DVI display card, they’ll need to change the connected channel of the KVM to "DVI re-trigger on.”

To check the status of the "DVI re-trigger" of each port/channel, simply push and hold the front button of the port until you hear a series of "beeps."

2 beeps = DVI re-trigger is "ON", 
3 beeps = DVI re-trigger is "OFF"

To change the setup of each port:

  • Push and hold the front button of the port you want to change until you hear the beep(s) sound accordingly
  • Then, quickly release the button.

In some cases, it might have accidentally been changed to DVI re-trigger "ON" on any particular port of the KVM switch. To change back to "OFF,” simply:

  • push and hold the front button of any particular port until you hear the 3 beeps
  • Then, quickly release the button.
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