What is the root cause of AMD 6xxx issues (white screen)

[partimers]

Hello,

anyone knowing why users with Radeon 6xxx are facing issues, specially white screens upon booting with UniBeast? This card is supposed to work natively with OSX (at least it did in Lion). I suppose it is still natively supported on ML as there are several recent Mac with this GPU.

I have seen several tips to workaround it (GraphicsEnabler = no, deleting and re-installing kext ATI6000, taking the GFX card out, etc), but I wonder what is the exact cause of the problem. Is it a faulty kext?

Tks for your answers!

 

[Bruno21]

I'm curious too !!

 

[KillerBuzz]

I'd also love to know...

 

[acehuldarr]

It's also of interest that some of the lower-end 6xxx cards are re-branded 5xxx cards. Many brands of 5xxx cards that worked fine in Lion now boot with full resolution but no QE/CI. There has to be a root cause for all of these shenanigans.

 

[reichleyusaf]

AMD 6xxx FIX

Gents (and ladies, if you're out there "hackin'" it up),

I ran across this issue myself when starting a clean install of ML yesterday. I can't pin down EXACTLY where in the forum I found the idea but when I do I will give proper creds. Anyways, I have a Gigabyte Z77X-UD5H, Gigabyte Radeon HD 6850 1 GB (overclocked), and the i7-3770K. After experiencing the white screen a couple times (tried GE=No, Yes, didn't mess with .kexts), I ended up plugging my monitor (HDMI) into the motherboard and unplugging the HD 6850 power plug. After installing using motherboard (I don't think that I had to use the 'GraphicsEnabler=No' switch for the motherboard), I plugged in the HD 6850 and plugged my monitor into the graphics card (HDMI port). I then booted back into Unibeast (new ML hard drive) USING the 'GraphicsEnabler=No' switch and ran MultiBeast. The most important part of correcting the video card issue is adding ATI keys to the chameleonboot.plist (in the /Extras folder) so every subsequent boot goes off without a graphics hitch. I posted a response with the boot.plist switches at the link provided.

http://www.tonymacx86.com/graphics/57150-replace-hd4850-hd6850.html#post367881

<key>AtiConfig</key>
<string>Bulrushes</string>
<key>AtiPorts</key>
<string>4</string>
<key>Darkwake</key>
<string>0</string>
<key>GraphicsEnabler</key>
<string>Yes</string>
<key>Kernel Flags</key>
<string>arch=x86_64 npci=0x3000</string>

 

[JoshNYC]

Bump.

 

[leeyee]

same issue to me.

then I change two flags in BIOS setting

Init Display First = Onboard
Onboard VGA = Always Enable


after reboot, everything works fine and no more white screen.

 

[monteolsen1]

I think the UniBeast info for this series of adapters may be faulty. (The Kexts, I guess.) I used a workaround similar to others in that I installed an nVidia GT260 in place of the 6870 until the install completed. After installing the 6870, Mountain Lion ran just fine. I have to admit that the screen definition is sharper with the nVidia card for some reason.

 

[FishCow]

I'd also like to know what the root of the problem with this kext is.
I have a Powercolor 6870

However, after getting ML installed - Open CL is working again (luxMark doesn't throw up errors anymore and works).
Everything looks nice and crisp and just seems to run better.
Lion 10.7.4 was terrible.

 

[objective-x]

Likewise, I'm curious as to what the situation is. I'm ready to start a build tomorrow... I've got a Sapphire 6850 still in the box, but no integrated graphics (got an Ivy Bridge Xeon). I'm wondering if I should send it back and get a nvidia GT 640 instead to get native support....