Originally Posted by NismoTuned
I already have Vsync off. What kind of gains were you seeing when you switched from very high to high? I was thinking about switching from 16x af to 8x but I honestly know nothing about AF so I don't know which to choose. I do know it doesn't effect performance too much.
I gain about 10 fps average from dropping to High, and 10 more if I lower the draw distance and detail distance sliders to 50% (with vehicle density still at 100). This combined gives me an average 45-50 fps compared to 30 fps at maxed settings. Since you have a much faster GPU \ CPU combination than I do, however, you're not likely to get nearly as much of a gain from lowering settings as I do.
45 fps is more than playable for GTA IV, and although it's ridiculous that a five year old game doesn't run better than that on a PC like yours, you're not going to gain more than a couple of fps by dropping settings without making some serious sacrifices in graphical quality that just won't be worth it. You should just keep it at maxed settings (unless it stutters) and be glad it still runs as well as it does.
A tip about AF for games in general: turn it to 16x on any game you play. It's subtle in what it actually does (read the Wikipedia article
on it for a description and examples), but it's also very inexpensive on modern hardware and barely dents your framerate. This is especially true for games that have it as a setting in the options menu like GTA IV, since those games were designed to use it.