4 ms·Check if Optimus can be disabled in the BIOS. It often can.by noamsml 15y agoCheck if Optimus can be disabled in the BIOS. It often can.Iv 15y agoIt canont on mine, Asus N73S with GT540MSymmetry 15y agoFor my T520 I can get by disabling Optimus, but then I can't use external monitors.