Help getting LED Cinema Display 24 to full resolution

[gerodotfour]

Successful build, running OS X Mavericks - trying to bring an old Apple LED Cinema Display 24 back to good use. Using the Multibeast 6.5.1 option "1080P Display Mode" I was able to increase the available resolution from 1024x768 to 1280x1024. But we're still not quite up to the advertised 1920x1200 for the LED Cinema 24.

I don't have a graphics card, just trying to use onboard video which should be able to drive monitors up to 2048x1536. From the computer, I have a DVI-to-DP adapter connected to a DP-to-miniDP adapter that then connects to the display's miniDP cable.

When booting into the bios and bootloader, all of the screen real estate is used - but in the OS, there are black borders around the desktop. I've tried holding down the option key while clicking on the "Scaled" button in System Preferences-Display. Guess that doesn't work with a hackintosh...

Please help, and thanks!

 

[gerodotfour]

Update: Using the Unibeast USB drive and boot option "Graphics Mode"="1920x1200x32" the screen resolution that OS X assigns to the display increased to 1600x1200. Not sure why or how that happened, as I typed something different, but this will only work when I boot from the USB stick w/ Unibeast. Do a restart and OS X boots from the hard drive, then it defaults back to 1280x1024. I don't know if I can program the above graphics forcing statement into the version of chimera on the hard drive or not, seems plausible...but now we seem to have an additional problem that only 4:3 resolutions are possible, so the vertical real estate is covered with the x1200, but the horizontal has black panes on either side since 1600 < 1920. The 1600x1200 is now the only option in System Preferences-Display, even if I hold the option button down...

Any ideas?