NVIDIA’s SLI Antialiasing Benchmarked

NVIDIA’s SLI Antialiasing Adds Clarity to Games

by Yaroslav Lyssenko

[ 07/25/2005 | 01:52 AM ]

While ATI has not yet commercially released its multi-GPU platform, NVIDIA widens the number of features available only to owners of multi-GeForce configurations. In order to meet ATI CrossFire platform fully equipped, NVIDIA has introduced additional eye-candy features in the latest beta ForceWare drivers which are available for download at nZone web-site. In particular, the most-recent flavour of the driver adds new SLI rendering mode – SLI antialiasing.

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“SLI Antialiasing is a new standalone SLI rendering mode that offers up to double the antialiasing performance by splitting the antialiasing workload between the two graphics cards. When enabled, SLI Antialiasing offers 2 new antialiasing settings: SLI8x and SLI16x,” claims NVIDIA’s statement.

The question which a number of web-sites have decided to address is whether 16x and 8x antialiasing modes really provide image quality benefits and whether performance in such modes is still decent to play games.

“Take, for instance, the case of the 8X SLI antialiasing mode. This mode is actually a doubled-up version of NVIDIA’s 4X multisampled antialiasing method. Each card renders the scene with 4X multisampled antialiasing, but their sample positions are slightly offset, or jittered, to make them distinct from one another. The two resulting sets of samples are then combined, yielding eight coverage samples and two texture samples, which are blended to achieve the final pixel color. The result should be the equivalent of NVIDIA’s familiar “8xS” antialiasing mode, except that the sampling patterns for SLI AA are a little bit different,” explains The Tech Report.

“One feature that is incredibly important is that SLI-AA works with nearly every game out there. No matter if it is Direct3D or OpenGL, or if it has problems with SLI AFR or SFR modes, the application will benefit from these antialiasing modes.  NVIDIA is promising a 100% compatibility with all 3D games with the SLI AA modes.  If the game can run on NVIDIA hardware, it can run with SLI-AA. Except of course games that do not support antialiasing in any way (like the first two Splinter Cell games) or applications utilizing FP16 HDR rendering (Splinter Cell 3 and Far Cry),” writes PenStar Systems.

“Doing some performance testing, we found many situations where SLI 8X and 16X AA modes were playable. Half-Life 2, for example, is very playable at 1600x1200 with SLI 16X AA mode. Where these Antialiasing modes really come in handy is in CPU limited games. For example, a game like Flight Simulator 2004 lets you enable the SLI 8X and 16X AA modes to experience much better image quality with a very small performance hit as this simulator is CPU limited and not GPU limited. There are also many older games where performance is very fast on the GeForce 7800 GTX SLI setup. Therefore, these new AA modes should also work well in older games,” concludes [H]ardOCP.

• nZone: ForceWare Version 77.76 Download.
• SLIZone: SLI Antialiasing: Redefining Image Quality.
• [H]ardOCP - NVIDIA SLI Antialiasing.
• PenStar Systems, LLC: NVIDIA Forceware 77.76 Preview.
• The Tech Report: SLI antialiasing debuts.