Fillrate and shading
Here's a collection of GPUs across the pricing spectrum.
| Card | SAPPHIRE X800 GTO | SAPPHIRE X800 GT | ATI RADEON X800 XL | ATI Radeon X850 XT | GeForce 6600 GT | GeForce 6800 GT | GeForce 7800 GTX |
| Native interface | PCI-Express | PCI-Express | PCI-Express | PCI-Express | PCI-Express | AGP | PCI-Express | Onboard memory | 256MB | 256MB | 512MB | 256MB | 128MB | 256MB | 256MB | Core speed | 400MHz | 475MHz | 400MHz | 520MHz | 525MHz | 350MHz | 430MHz | Rendering pipelines | 12 | 8 | 16 | 16 | 8 | 16 | 24 | Fillrate (multi-texturing) | 4.8GTexels/s | 3.8GTexels/s | 6.4GTexels/s | 8.32GTexels/s | 4.2GTexels/s | 5.6GTexels/s | 10.32GTexels/s | Memory interface | 256-bit | 256-bit | 256-bit | 256-bit | 128-bit | 256-bit | 256-bit | Memory speed | 980MHz | 980MHz | 980MHz | 1080MHz | 1050MHz | 1000MHz | 1200MHz | Memory bandwidth (max) | 31.36GB/s | 31.36GB/s | 31.36GB/s | 34.56GB/s | 16.8GB/s | 32GB/s | 38.4GB/s | Average online price | £130 | £110 | £265 | £225 | £105 | £175+ | £330 |
The cards' performance we're most interested in fall into the sub-£150 catergory. That includes the X800 GT 256MB and GeForce 6600 GT 128MB SKUs. Further up the pricing scale comes the GeForce 6800 GT 256MB, available for around £175 with AGP and £200 for PCI-Express, which is the rough price for a 256MB-equipped X800 XL. Remember, it only differs, performance-wise, from the X800 GTO 256MB SKU by having a full four-quad (vs. three-quad) rendering setup.
Single-texturing performance is rather poor. Multi-texturing performance, however, is above both a GeForce 6600 GT's and the X800 GT 256MB's. An X800 XL 256MB produces a fillrate that's roughly a third higher. We'd expect that, given that it has 33% greater pixel-pushing power. The GeForce 7800 GTX slays all.
Take away the results of the GeForce 7800 GTX for a second and you'll see that pixel shading performance is actually reasonable.
ATI always hits back with its SKUs' vertex shading ability. No change here. The X800 GT 256MB SKU outperforms the GTO for the simple reason that its core is clocked faster, at 475MHz vs. the GTO's 400MHz.
