nVidia GeForce GT200 Series Anti-Aliasing Investigation
CSAA Anomalies
I mentioned in the CSAA section that if coverage sampling fails for a given pixel, it falls back to the base multi-sampling mode. However in practice I’ve found a few rare cases where the AA quality is much lower than the base MSAA level.
Here’s an example from a zoomed shadow edge from Doom 3. You can see 16x actually looks closer to AA being off, while 4xAA is much smoother in comparison.
0x
4x
16x
This example is indeed visible to the naked eye while gaming; I actually spotted this while playing through Doom 3 again at 2560×1600, so I stopped the game to take some screenshots.
I’ll repeat that these situations are extremely rare, but are nevertheless interesting because CSAA theory can’t explain them.
I run 2560×1600 with 2 gtx280’s and something very noticable was how much smoother all games run with AA (all in game no need for Nvidia control panel) when I upgraded from Vista 64 to Win 7 64. Games like Crysis and COH at 2560×1600 everything maxed with 8xcsa wouldnt even render a frame with Vista, after upgrade to WIN 7 64, COH and Crysis run 16x NP, (Cryis with low FPS obviously) SLI 285’s and 280’s Win7 is the way to go.
Yes, Windows 7 handles SLI/CF better than Vista.