External Monitor (screen resolution issue) with Macbook Air 2011 with Lion

Apply the MBair EFI update available on Software Update and see if that changes anything.

Regards,

Captfred

I have the same problem - it does not output to 1680x1050 even after I've applied the EFI patch. I'm using a DP to VGA adapter connecting to a Dell 22" 1680x1050 display.

Just letting you know that my external display can go all the way up to 1920*1200 without problems with a MiniDisplayPort-HDMI converter. EFI update does not seem to be the issue.

The problem is not it cannot go up to 1920x1200. The problem is that it cannot display certain wide-screen standard resolutions such as 1680x1050, 1280x800, etc.

I understand your problem. I'm just trying to tell you this is unlikely a bug of Lion or EFI upgrade.

I agree that the problem is not necessary a bug. For example, I tried to use a DP to HDMI cable to connect to a TV and it can properly detect the kind of TV and a set of resolutions supported, etc. I'm thinking that the EDID is not communicated through the VGA interface (which the monitor is supposed to be able to as it can do so to a PC running Windows or Linux - may be the TB/DP interface with VGA does not support that). Then, Lion probably just use a default set of pre-defined resolutions and frequencies. If that default set can be expanded to the other resolutions, it would be great. The question is how to add those even on my own. Application such as SwitchResX allows you to add customized resolutions but that application is too buggy for Lion. I'm pretty sure once you know the trick on where and how to add those extra resolutions, it'll just work as it appears that the developer of SwitchResX knows the trick 🙂. XWindows made such set customizable since day one but I'm new to Mac OSX so I'm trying to figure out where to make such changes - if they are documented somewhere (perhaps in the SDK?)

I can diagnose to the point that there is a VGA cable problem in which it is not passing the EDID info to MBA. Once I switched to a different VGA cable, it can display the resolution properly, in 1680x1050 or 1280x800.