Sorry for posting it at the wrong place.
I managed to get both first DP and HDMI working following guides from Rehabman and Toleda and many others. But I still have no luck enabling the second display port.
It seems I can either enough DP1 + HDMI or DP2 (with messed up framebuffer-portnumber...
this is the modified version of clover, patches EDID on the fly to eliminate the infamous second stage garbled screen issue, tested on my HD4600 laptop
1. remove any modification under /System/Library/Displays/Contents/Resources/Overrides
2. use plist editor add corresponding items...
I can use remote desktop to access so seems everything else works fine except for the display.
once the patch is removed my lcd works as usual. (however I do miss the slightly bigger resolution)
anyone else had the same issue?