I have an iMac (2011) with a Samsung SyncMaster SA350 connected. I originally connected it using Mini DisplayPort -> VGA. The iMac detected the display and it showed a very clear image.
Then I decided to move my Xbox 360 to my desk. It also connects via VGA. Since my monitor only has one VGA input, I decided to get a 2 port VGA switch to avoid plugging and unplugging every time. Problem is now my iMac just detects the display as "VGA Display", which results in a not very nice looking image.
I have tried rebooting several times. Both with the switch enabled to the iMac and to the Xbox 360. Only thing that has worked is unplugging the iMac from the VGA Switch and plugging it straight into the monitor again, and then plugging it back into the VGA Switch. But once the iMac has shut down and gets turned on again, it's back to the crappy VGA Display settings.
Now the Samsung monitor also has a HDMI input. I tried getting a Mini DisplayPort -> HDMI cord off eBay. But no video signal came through from the iMac. The cord itself is not the issue as it worked fine when I plugged my MacBook Pro into my TV.
My Xbox 360 is an old model, so it doesn't support HDMI either.
Is there any way to get the iMac to detect it properly as the Samsung display it is and use those settings for video output?
Not sure if it makes any difference, but I'm running OS X 10.7.5 (Lion)