There is a lot of Graphics Problems with the DELL Latitude E6220. There seems to be a lot of dashes and marks on the screen when you boot up with the Extra Folder from this website. I think there is a problem with the DSDT file.
I am debating about buying a Dell Latitude E6220. I have a choice of the i5 or the i7. According to your guide it requires an i5. Will your guide work with an i7? Do I have to do anything special to the DSDT to make it compatible with an i7?