Can I do the dual graphic (use two same monitor, the monitor 1 is next to monitor 2, monitor 1 use the graphic card, monitor 2 the mainboard graphic) on Ubuntu? What driver I should install to do the dual graphic?
Mainboard graphic: HD2500 (from Intel Core i5-3450)
Graphic card: ATi Radeon HD 4850
At least in my case, no you can't.
First, using multiple different vendor graphics cards, while theoretically possible, is riddled with problems.
This part has been asked before, but I can't seem to put my hands on the question
Second, most of the time on-board graphics is disabled when the motherboard detects a secondary video card inserted.
Third, even if it were possible you would run in to similar issues to what vga_switcheroo, bumblebee, and ironhide all try to address.
While they are a little different since they address hybrid graphics cards, I would imagine there would be similar problems.