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I have a new machine with a recent video card (ATI Radeon HD5850) connected to an Acer H233h monitor with a native resolution of 1920x1080 through a KVM (switch keyboard)

At first, as the KVM don't forward the plug&play information from the monitor, it's seen as a 'non-plug&play monitor' and the maximum resolution proposed is 1600x1200.

I have installed the driver of the monitor (H233h.inf) and now the 1920x1080 is available but when I select it, the refresh rate is set to "30Hertz interlaced" and the image on the screen 'tremble' which make it unusable.

I have tried to modify some parameters in the inf file to adjust the horizontal and vertical refresh of the monitor but without success ...

Please note that I have other machines connected through this KVM (a WindowsXP and a Linux machine) and they use 1920x1080@60hz without problem

Note also, that when I connect directly the monitor to the video card (removing the KVM from the loop), Windows automatically recognize the monitor and display 1920x1080@60 without problem (but I need to use this KVM, as I don't have enough place to have an other monitor/keyboard/mouse)

So I'm nearly sure that the problem come from the .inf file.

What can I do to use the maximum resolution of my monitor ?


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To me , it seems that you will need to get a KVM that support Plug & Play.
According to the Display Guidelines for KVM Switches in Windows 7 , the KVM needs to pass the EDID and DDC information.
I suspect that your current KVM is not compliant with the Windows 7 guidelines.

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Yes, for sure my KVM is pretty old and don't support Plug&Play. I know that since a long time and it's certainly the root of the problem But I can make it work without trouble from Linux and from WindowsXP by declaring correctly the parameters of the monitor. So there should be a possibility to do the same in Win7 – ericc Jun 23 '10 at 11:01
@ericc - Windows 7 is not Windows XP. Just because something could, in theory, work, doesn't mean you can make it work with available tools. They're enforcing restrictions for a reason. That said, there should be some way to spoof an EDID for this thing...I know the newest nVidia drivers let you do that. – Shinrai Dec 30 '10 at 18:26

Use DDC EDID emulator to clone the EDID info of you monitor and put it between your Windows 7 system and KVM switch. So, the emulator will keep feeding the EDID information required by Windows 7 no matter if you're on the target system or not.

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