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Forums -> Multiple monitors -> Dual display, 4-port DVI KVM, primary and secondary confusion
Pieter   2005-12-29 16:16
Google pointed me to this forum, so maybe somebody has advice...

I want a dual display 4-port DVI KVM switch supporting 1900x1200. Unfortunately I have yet to find one.

Instead I am currently trying a Gefen 4 port DVI/USB KVM that supports 1900x1200. See http://www.gefen.com/kvm/product.jsp?prod_id=2796

To obtain dual monitor support I use two KVM's, one for each monitor.

I am testing with two DELL OptiPlex GX620 machines, each with an ATI X600 256MB PCIe dual DVI card supporting 1900x1200, and two DELL 2405 24" displays.

Here is the strange bit:
- Connect the X600 directly to the monitors, and all is well.
- Connect primary output only through the KVM, secondary output is disconnected, and all is well.
- Connect one output only through the KVM and the other directly to the monitor, and the primary output (the POST boot screen) switches to the secondary monitor, and the primary monitor has interference (red flashing lines or a green tint).
- Connect both outputs through the KVMs, and the primary output (the POST boot screen) switches to the secondary monitor, and the primary monitor has interference (red flashing lines or a green tint).

I have never seen a VGA card that switches primary and secondary displays, and why the KVMs cause the output switch and the interference I don't know.

I tested with a third new KVM switch, and the behavior remains the same.

I can only conclude that the KVM and the VGA card does not "like" each other when both outputs are used.

Anybody have any ideas on how to fix this, or anybody know of a dual monitor DVI/USB KVMs suporting 1900x1200?
Forums -> Multiple monitors -> Dual display, 4-port DVI KVM, primary and secondary confusion

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