Resolution Issue at POST, Clover Boot & Login Screen

[rocco_77]

@rocco_77 Lots of technical info here, only thing I can add for now is :

- check the dvi cable, at least try another cable, or go hdmi (which is nice to have audio if that's relevant to the setup)
- if the video card has dual bios, try the other setting. (My 580 can do opencore at higher resolutions using the normal bios, but the higher performance bios setting gives a lower res at the bootloader.)

I have a feeling it just might be the monitor / cable. The Apple Cinema displays are old, but so is the card. And it did this to me when I updated to El Capitan, and then it just seemed to fix itself then... But this time it's not. I've given up for now and I'm just using the onboard graphics. I just finished building another Hack. I'm replying to this on the new machine. My old machine will be used in the bar I own for Karaoke now... so the onboard graphics are just fine.

I'm going to make a build post about the new machine. Super excited. Using Opencore 0.7.0. That was a learning curve, but very much worth the effort as everything works. And it's dual boot on separate drives with Windows.