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MBP 15" 2011: Forcing external display through Intel graphics?

R

Roman2K~

macrumors 6502a
Original poster
Mar 11, 2011
552
16
Hello,

I have got a Sandy Bridge MacBook Pro, 15" with a 2720QM and 6750M -- absolutely love it, perfect in every way.

Only I have an external "monitor" connected to it via HDMI, a 32" Philips LCD TV that doesn't like AMD graphics cards. Every 20-30 minutes, colours turn to green and pink. A number of people have noticed this, so I am not alone. No problems with an nVidia GPU (tested with a mid 2010 13" MBP, equipped with a 320M).



It's because it doesn't like the YCbCr pixel format (at least not coming from AMD GPUs). Under Windows, exact same behaviour by default. Switching to RGB 4:4:4 fixes the problem entirely.

I am left with two choices:

1. Switching to RGB 4:4:4 on the external display output. I haven't found a way to do this, but from Google results, AppleTV has this settings so chances are it's present in the regular Mac OS X, only buried somewhere. Is there such a setting?

2. Bypassing the discrete AMD GPU, and use the integrated Intel GPU instead for the external display. Again, no such setting but this time, I'm almost certain that the hardware is wired so that the external display output only goes through the discrete GPU. Hopefully I'm wrong. Is it possible?

Any help would be greatly appreciated.
Thanks.
 
Last edited:
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Wish I could help, also edit your post (Don't just bump)
 
Report the issue to Apple. Maybe they will include it in the next patch for OSX. Currently I don't know of a way powering an external display with the integrated GPU on the 15" or 17". It should be possible though, the 13" does it perfectly well.
 
On the 2010 MBP with discrete graphics cards (15" & 17") the integrated graphics card is not wired to the display port. System Profiler confirms this. When you get information for the integrated graphics card it shows only one display connector. The discrete graphics card shows two display connectors, one that powers the laptop lcd, and another that controls the display port. I can't be sure, but I am fairly confident that the 2011 models work the same way. You can check system profiler under displays/graphics to be sure.

Your best bet would be finding a way to switch to RGB, or hope that Apple at some point updates the driver.
 
Hi, have you ever resolved the issue? I experience exactly the same problem with my Sony bravia LCD. I have read, that Apple TV suffered the same flaw but got fixed in new IOS version, I wonder if it is the same issue.
 
macmilan said:
Hi, have you ever resolved the issue? I experience exactly the same problem with my Sony bravia LCD. I have read, that Apple TV suffered the same flaw but got fixed in new IOS version, I wonder if it is the same issue.
Click to expand...
Unfortunately, no.

I tried plugging the same TV to a 2011 13" MBP (output through its only GPU, Intel HD 3000): same problem. So it's not specific to AMD GPUs. Even it it was possible to output via the 15" MBP's HD 3000, it would have no effect. However, no such issue with a 2010 13" MBP, equipped with an nVidia 320m.

iOS for Apple TV has settings for switching to RGB, which solves the problem with our TVs.

I'm pretty sure the problem comes from the TV. I sent mine for repair, I should get it back tomorrow. Allegedly, they found the problem and fixed it... :rolleyes:. I'll believe it when I see it. It was more of a way for them to avoid replacing it with a new, different-brand working one.
 
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