y580 lenovo ideapad

Hi, After upgrade from Yosemite to Sierra 10.12.4 Nvidia 660M no longer works. System lost it completely. Is there some possibility to enable it back because it was faster then HD4000. Thanks in advance for your help.

Hey Guys i come from Germany and i hope its not a Problem when my english is not so good. Ich have an Lenovo IdeaPad Y580 with an i5-3210M, 8GB, 750GB HDD, 128GB SSD I have many kext Installed and 90% of all Parts Works but the Sound is wery bad and the Sleep Mode doen´st work. In an other Tread...