I would really apprecaite your help on this.
Besides, in case of any problem with my monitor, I believe it would be safer to have 800x600 mode. I guess it'd be better to replace another "less useful" resolution, perhaps 1152x864. How can I do that?
Edit: another reason, look what happened to my BIOS screen (previously, it was
Edit2: I managed to replace 1600x1200 with 1920x1080, so BIOS went back to normal, but I still have those borders.
Went to the effort of patching the VBIOS and Chimera now displays in 1920x1080 however it is surrounded by black borders, this is underscan.
So yes, it seems the video adapter is outputting 1080p like you have told it to with the VBIOS edit and your .plist, however it's also taking and scaling down that display resolution. For example, if I install a fresh Catalyst Control in Windows I also get this underscan after the first reboot, you have to go into the CCC scaling options to change it. However this does not work for boot.
Maybe there is something in the Chameleon/Chimera source that references the default underscan? Or else maybe there are some bytes we can edit in the VBIOS to set/clear the default underscan?
I'm not sure if it's relevant but the issue seems to exist on Linux distro's and has been solved there. The Arch Linux Wiki refers to it:
When I connected my TV to my Radeon HD 5770 using the HDMI port, the TV showed a blurry picture with a 2-3cm border around it. This is not the case when using the proprietary driver. However, this protection against overscanning (see Wikipedia:Overscan) can be turned off using xrandr:
xrandr --output HDMI-0 --set underscan off
I know it's only cosmetic and we only see the bootloader for a second, but I'd love to get this right after putting so much time into it.