Explanation:
In series 6 chipsets the MEI (Management Interface Engine) has device-id 0x1C3A but in series 7 chipsets it has device-id 0x1E3A so that the AppleIntelMEIDriver does not match the device and won't load, but without AppleIntelMEIDriver running AppleIntelHD3000Graphics.kext won't be able to recognize the Framebuffer, times out and unloads itself leaving you without graphics acceleration. Adding the correct device-id enables loading of the driver.