The Voodoo5 5500 is effectively functioning in AGP 1x mode as AGP bandwidth is shared between both graphics processors i.e. texture and vertex data are duplicated across the AGP bus. It is also incapable of receiving textures from AGP memory directly (AGP texturing). By configuring the 'Speedway' scene to use uncompressed textures (16.4 megabytes) at a high resolution and color depth (1600x1200x32), a significant portion of textures cannot reside in local video memory. These textures are stored in AGP system memory or main system memory and need to be drawn across the AGP bus.
By configuring the 'Speedway' scene to use uncompressed textures (16.4 megabytes) at a high resolution and color depth (1600x1200x32), a significant portion of textures cannot reside in local video memory. These textures are stored in AGP system memory if AGP texturing is supported or system memory if AGP texturing is not implemented and need to be drawn across the AGP bus.
As the peak AGP bandwidth of the Voodoo5 5500 is effectively half that of the GeForce2 GTS in AGP 2x mode, AGP transfer is slower than the latter. The difference in AGP transfer rates is especially marked if AGP texturing is enabled for GeForce2 GTS (Fig. 4).