Quote Originally Posted by Eastcoasthandle View Post
It is my understanding that screen space ambient occlusion mods have been out for HL2 for some time now. Here is one example specifically for G80 (according to the author) but there are plenty more. Also, I recall that this can be implemented without having to alter .dll info.
Yeah I saw that. My copy of HL2 is not modded however so it seems the drivers are doing something similiar to what the mod did.

This confirms my inital opinion. This option appears to be similar to having the option to enable EATM in some games using a radeon video card (foilage, etc). My only question is if this has any negative impact to IQ and/or increase in frame rates if AO is disabled for games that use AO by default?
Don't think it works like that. AO isn't an API or hardware feature. It's just a pixel shader. Don't think the driver can "disable" a shader submitted by the application. And even then, how would it know which shader to disable?