On my N55SL, which has a HD3000 on its i7-2670QM, AGPM will not load under 10.8.3.
I am using a MacBookPro8,2 definition in my smbios.plist as it's the one that matches my laptop the closest (they're both 15" and there's a 2675QM model -- the only main difference is that the 8,2 uses an ATI switchable graphics, while I have an NVIDIA chip in my laptop. This is of no difference in reality, however, as the 635m is turned off in the DSDT) with a serial number that validates.
I have already changed the IGPU entry inside the MacBookPro8,2 entry in /System/Library/Extensions/AppleGraphicsPowerManagement.kext/Contents/Info.plist to Vendor8086Device0116, which should let it load - yes, I've already checked with IORegistryExplorer and those are the correct values. I also removed the other two entries that were, presumably, for the ATI GPU in hopes that it would start working but to no avail. (Previously, I was using an unmodified AppleGraphicsPowerManagement.kext and had renamed the Intel GFX0 - not the NVIDIA GFX0 under Device (PEG0) - inside my DSDT to IGPU but this didn't do anything, also, so I reverted it back to GFX0 for simplicity's sake.)
If I look at an IOReg dump from a real MacBookPro8,2 (which has the 2675QM as far as I can tell from its serial number), I see that under IGPU->AppleIntelFramebuffer@0, AGPM->gpu-control->IOHWControl exists - I take it that AGPM is capable of running on this hardware. On my IOReg dump, AGPM is nowhere to be found. (I do have two additional framebuffers listed on my laptop, but no display is connected to them - does anybody know if AGPM is hardcoded to only work with HD3000s that are only presenting one framebuffer to OS X?) dmesg doesn't list any entries for "AGPM". In Console, a filter for "AGPM" also results in zilch. "sudo kextutil -v -t /System/Library/Extensions/AppleGraphicsPowerManagement.kext/" doesn't result in me seeing any useful information (and AGPM.kext immediately unloads).
Although I cannot see the entry for myself in the ASUS BIOS, if I look at the latest BIOS image with AMIBCP, "Gfx Low Power Mode" is enabled with both the optimal and failsafe configurations, so it should be enabled anyway.
While it's not a huge deal to me to have it working (I only get 2 hours on battery anyway and the laptop never gets hot under OS X anyway), it would be great if I could.
I've attached a copy of my original DSDT, along with a diff of the changes to it that result in the DSDT that I am using on my laptop to run OS X. Chameleon r2187 is installed with GraphicsEnabler=No. Thanks.