My display is white with waving vertical lines at boot up last thing I did was to open dota 2 tried an external monitor and it only gives me black screen I'm suspecting a faulty videocard as my laptop is stationary and barely moved. But i remember I have igpu i5-3210m and gpu ATI 7670m laptop model: Toshiba Satellite l850 B757. Why does the igpu doesn't work or my suspected component is wrong?