Compare any two graphics cards:
GeForce 9800 GX2 vs Radeon HD 4890 2GB
IntroThe GeForce 9800 GX2 comes with a GPU core speed of 600 MHz, and the 512 MB of GDDR3 memory runs at 1000 MHz through a 256-bit bus. It also is comprised of 128 SPUs, 64 TAUs, and 16 Raster Operation Units.
Compare all that to the Radeon HD 4890 2GB, which features GPU core speed of 1000 MHz, and 2048 MB of GDDR5 memory running at 975 MHz through a 256-bit bus. It also is comprised of 800(160x5) Stream Processors, 40 Texture Address Units, and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The GeForce 9800 GX2 should in theory be a bit faster than the Radeon HD 4890 2GB overall. (explain)
Texel RateThe GeForce 9800 GX2 is a lot (approximately 92%) more effective at texture filtering than the Radeon HD 4890 2GB. (explain)
Pixel RateThe GeForce 9800 GX2 will be a little bit (about 20%) more effective at anti-aliasing than the Radeon HD 4890 2GB, and will be able to handle higher resolutions without slowing down too much. (explain)
Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.
One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.
Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.
Memory Bandwidth: Memory bandwidth is the largest amount of data (counted in MB per second) that can be transferred across the external memory interface within a second. It's worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.
Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.