Problems with resolution when using external monitor [MBP]

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Hi there:

First of all thanks for having and contributing to this great forum. Its been a fantastic resource for me with all kind of stuff.

I recently bought an external monitor since I am tired of using the 13" screen on my MacBook Pro. I connected the monitor via a DVI-D cable and the DVI adapter from Apple. So far so good but here is the problem:

When running the monitor as a second screen and I drag over a browser window the resolution is crisp and sharp. As soon as I switch to mirror mode the resolution is off. The max resolution of the monitor is 1920 x 1080 (Acer S240HLbid 24 inch Full HD widescreen LCD monitor with LED Backlight (16:9, 100,000,000:1, 1920 x 1080, 5ms, HDMI/DVI) - Black: Amazon.co.uk: Computers & Accessories) but it seems that the maximum resolution given from my MBP is only 1600 x something when mirroring.

I read through plenty of posts and I have tried using closed clamshell mode and it actually works then! However, I was wondering whether there is any way of getting the correct resolution on the external monitor while keeping my Mac open?

Thanks for those that are reading this post and special thanks to those answering :)

Regards!
 

Slydude

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I am still working to completely confirm this but I think it has to do with the MB Pro resolution.I think that when in mirror mode the MacBook Pro extends its resolution to the external monitor. In short the monitor can inly use the laptop's highest resolution when mirrored (unless it is in clamshell mode). Mirror mode with Dell 2410 problem - MacRumors Forums
 
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Thanks Slydude! I did even more research in the meantime and it does appear that the only way(s) to get the correct resolution on the external monitor is to use it in clamshell mode or as an extension. Well, I guess I will / have to get used to it. :)

I am using a raise stand for my Mac so there shouldn't be any problems with overheating even when the lid is closed, right?
 

Slydude

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I don't think there would be though I can't say for sure. I am using an elevated stand and external monitor but I typically run inn extended mode. Rarely use clamshell.
 
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For people that are interested / have the same "problem":

When the lid is closed the fan actually does turn on quite often (definitely more than usual). However, in my case I reopen the lid once I woken up the Mac with the mouse and the external screen is active. The notebook screens stays off then and there is no issue with overheating anymore.

I must say though that I still run Snow Leopard (for a variety of reasons) and I heard under Lion (or even Mountain Lion) this little trick doesn't work since the notebook screen will turn on when opening the lid again.
 

chscag

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I must say though that I still run Snow Leopard (for a variety of reasons) and I heard under Lion (or even Mountain Lion) this little trick doesn't work since the notebook screen will turn on when opening the lid again.

Not true for Snow Leopard and Lion. (I can't speak for ML as it's still in beta) I ran both Snow Leopard and Lion in clamshell mode and had no problem with leaving the lid up once the machine booted and the external display activated.

I suspect the same will hold true for ML unless Apple changes that in future versions of OS X.
 
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I didn't say that it doesn't work for Snow Leopard. I use SL and it works. I just heard that it doesn't work with Lion. Anyway, good to know that the open lid works under all OS versions. :)
 

chscag

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OK, I guess I misunderstood your first reply. Yes, it does work OK with Lion but as I stated, it may change with ML, although I doubt it.
 

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