X-bit labs

S3 Chrome S27 Graphics Processor Review: Worthy Performance for Its Class? (page 6)

Category: Video

by Alexey Stepin , Anton Shilov

[ 12/29/2005 | 12:11 PM ]

Anisotropic Filtering Quality

The anisotropic filtering algorithm implemented in the Chrome S20 series has been improved since the previous products from S3.

The filtering quality has remained high, but the samples seem to be now taken not from one mip level like on the DeltaChrome and GammaChrome, but from all levels like GPUs from ATI and NVIDIA do. As a result, the problem with the coloring of mip levels has vanished. This may have a negative effect on the performance of the Gamma S27, but it is not likely to be noticeable at the 700MHz GPU clock rate.

We’d want to note that the anisotropic filtering method from S3 Graphics doesn’t have “inconvenient” angles of view and, as a result, produces a better-looking picture in some games than the methods employed by ATI and NVIDIA do. Moreover, the mip-levels on the Chrome S18 and S27 begin at a rather big distance. This makes the textures sharper, but may sometimes result in the annoying “grainy” effect.

Theoretical Tests

Scene Fill Rate

The S3 Chrome S27 boasts a high fill rate due to its high core frequency, even though its 8 pixel pipelines are accompanied with only 4 TMUs and 4 ROPs. The card has some problems when it comes to work with the Z-buffer, though. The fill rate goes down and we can’t explain why. For example, we can’t blame the ROPs because the NV43 (GeForce 6600) has the same number of ROPs. Low efficiency or small size of the Z-caches or some specifics of the ROP architecture probably lead to this result. In other cases, even at mapping four textures simultaneously, the new graphics card is head above its opponents.