I think it has two separate cards, because the display goes black when its switching betwen them. The intel one is completely fine on my eyes, but too slow for any graphic work. I think the driver is faulty, or in worst case, maybe the HW of the card is just going bad and the card itself is faulty.
Im gonna try to clone the system restore partition to another drive, and then install a new system on it with factory settings and see if the drivers work well then.
Still, the fact that a faulty driver can cause migraines and eyestrain on a system that was good for years, is just completely beyond me. It adds another variable to a very complicated problem already. Unless, of course, the faulty driver causes some bad dithering it did not before. I cannot test for that though.
EDIT: I tested with http://www.lagom.nl/lcd-test/black.php. On Intel card, it doesnt show the first three squares and the fourth one has a pattern of static dithering. On the AMD card, it shows the first squares, but the pattern is exactly like the one on the example of temporal dithering.
So I guess theres a proof that temporal dithering only can cause really annoying migraines in me. Flicker it is again I guess.