HD 5770 screen goes black after the Apple on Gray Background with Mount Lion

[poffen]

This all worked great with duel monitors, no problems at all. I switched to one WQHD/WQXGA and still using the HD 5770 with DVI-D cable and monitor goes black after the Gray Apple just as it is going to the login page. The system continues to boot and, here is the crazy thing, if I remove the DVI connector from the back of the computer and replace it, the screen comes up and it works great the rest of the day, but it just will not go to the log in screen on it own. All worked great from the first install through two updated to Mountain Lion, all with duel 24" Dell Ultra monitors. But is sure has a problem with one. 27" IPS monitor. Any help will be greatly appreciated.

GA-Z68X-UD#H-B3 F-12
Radeon HD 5770 1GB
16 GB Memory

 

[xofblade]

Hi,
I had the same problem and mine was solved by adding the text below to org.chamelon.Boot.plist in Extra,

<key>Graphics Mode</key>
<string>2560x1440x32</string>

Dont know if it will work for you, but it did for me. Big thanks to aaron97 for the info and helping me solve my problem!!

Regards Neil

 

[poffen34]

Thank You, Thank You and Thank You again. I have tried so many different combinations that didn't work and in some cases caused me a lot of work to get back to where I Had been. But This did the trick and works like a charm and I can't thank you enough.

 

[xofblade]

Hi,
no worries at all, also thanks to aaron97. He came up with the fix for me.
Regards Neil