dpg12

It's because the method already exists (look for "Method (_DSM, 4, Serialized)" somewhere around the 8000-9000 mark). You can replace the contents of that method. I haven't tested it as I have an N55SL, but there's a DSDT.aml with that patch already applied from here: https://github.com/a-anosov-parc/hackintosh-kexts-asus-n55sf/tree/master/10.8