OS X Auto Adjusting Screen Resolution - how to stop?

[Neilis]

Ok, I've got a minor annoyance here. Sometime between 10.5.1 and 10.5.4, OS X has started auto adjusting my screen resolution when it perceives a monitor change.

 

Example: I use a KVM switch so that I can use several computers with a single keyboard/monitor setup. When I have a specific display active, it picks up my monitor as a 1680x1050 display device. If a computer is not the active computer though, the KVM presents itself as a 1024x768 display device. It used to be that if I booted the machine while it was active, it would stay at 1680x1050 unless I rebooted. Now, when I switch away from the Mac, it reduces itself down to 1024x768. When I switch back, it switches back to 1680x1050. That wouldn't be an issue except that it does take a few extra seconds for it to adjust, and because the resolution "shrunk", a lot of my windows are now resized to a smaller size.

 

Is there any way to either a) disable this auto switching behaviour, or :censored2: just force it to always output at 1680x1050 regardless of what it auto-detects?

 

Thanks.

[master_macrex]

It caused by KVM switch which did not support DDC data communication among Display(monitor) and connected systems.

Simply find a KVM switch support Full-time DDC communication will solve this issue.

 

Looks like you have more than 4 computers connected to one display ?

[Neilis]

3 computers connected to this display (the Linux machine, the Windows machine, and the Hackintosh), though the KVM can support 4.

 

My G4 and another Windows machine are connected to a second display at my other desk via an older analog KVM I have.

 

I'd hoped that there was a way to correct this issue or disable the behavior. My Linux nor Windows machines do this, and the Mac didn't start until I moved up to 10.5.4. The KVM I'm using on this main station is an IOGEAR Miniview. I'm not too keen on replacing it as it cost nearly $200 itself and was my 3rd DVI KVM - the previous ones never quite worked as well as I'd like. This one has done very well for me for over a year, up until this last update.