Hi, I am using a Radeon HD 5870 with 10.8 drivers. With Ambient Occlusion turned on, in addition to low FPS (low 20's) and what appears to be graphical lag (the game feels like it stalls for half a second and lunges forwards...hard to describe), I get a large "shadow line" as depicted below. It begins in the upper left-hand corner and extends towards the middle of the screen where it fades out.
I had a similar issue in All Points Bulletin, though I never linked the cause to Ambient Occlusion, and the line was almost unnoticeable.
There was another topic here comparing AO off and on. He mentioned the right side of his screen being darker due to an ATI bug with AO, but the screenshot he linked didn't show any noticeable shadow line.
Is this an ATI only problem? Also, is it only ATI cards that run badly with AO turned on? I have seen several Nvidia users claim that AO hardly effects their performance, whereas it impacts mine a great deal. Even Nvidia users with lower specs are claiming to be using AO just fine. Of course, they provide no proof and if there's anything I've learned over the years it's to not trust what people say about their PC performance, but I'm not going to totally right them off. I'm more inclined to believe them, considering I keep seeing more and more people with Nvidia cards claiming to be running fine.
Edited, Sep 10th 2010 1:02pm by TheLufia