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AngieAndretti

M17x R4, 7970m, Disable Enduro causes Reduced LCD Color Depth; WHY?

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I noticed this the very first day I received my Alienware M17x R4 two years ago, and I ignored it until now but I now have a reason why I'd like to run with AMD's Enduro Switchable Graphics disabled. Doing so (Fn+F7 or equiv.) causes the built-in LCD to display a reduced color palette, even though it's set to 32-bit color on the desktop. There is also this weird interlaced look to the display in this mode - it's hard to capture with a camera but I'll attach a picture. 16-bit desktop color setting looks normal and there's no interlacing but 16-bit color sucks for Win7.

  1. Has anyone else observed this color depth reduction / display interlacing? (Discrete card is AMD Radeon HD 7970m)
  2. Why does it occur with Enduro off?
  3. Is there a fix or workaround to run in full discrete-only GPU mode and still have full 32-bit color so that Windows looks as good as it does with the Intel GPU?

Thank you!

post-7271-14494999599675_thumb.jpg

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Follow-Up: Does it have to do with display dithering or some other technique that Intel is using to fake more colors than my LCD can actually display?

My 1600x900 LVDS display is native 6 bits per primary color per pixel. I found an article that stresses how 6bpp can only result in a true representation of 262,144 actual colors - so Intel must be doing something with their GPU to make the display appear to represent more colors than it actually can, right? And when we connect the AMD GPU directly we are not getting this effect. Is there something I can change, perhaps a registry setting or Window display color profile, that would compensate similarly to whatever Intel is up to? Does this make sense?

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Further Examination reveals that it is display dithering going on on the Intel side, and tweaking the color palette in AMD's CCC can compensate for the color banding that makes the display look interlaced - so the question becomes:

How can I tell the AMD 7970m to dither the display colors like the Intel chip does?

There are many AMD-specific registry settings that affect how the display looks but I've yet to find a solution there... any thoughts?

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I have an HD display and I have none of these problems. Have you tried to output via HDMI using either enduro/7970m alone and see if there is some trouble there?

I know the last part of my answer doesn't help you but may delineate GPUs vs display problems

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