Compare any two graphics cards:
Radeon HD 4790 vs Radeon HD 4870 2GB
IntroThe Radeon HD 4790 features a core clock frequency of 600 MHz and a GDDR5 memory frequency of 800 MHz. It also makes use of a 256-bit bus, and makes use of a 55 nm design. It features 640(128x5) SPUs, 32 TAUs, and 16 ROPs.
Compare all of that to the Radeon HD 4870 2GB, which makes use of a 55 nm design. AMD has clocked the core speed at 750 MHz. The GDDR5 RAM runs at a frequency of 900 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 ROPs.
Power Usage and Theoretical Benchmarks
Theoretically speaking, the Radeon HD 4870 2GB should be 13% quicker than the Radeon HD 4790 overall, because of its greater data rate. (explain)
Texel RateThe Radeon HD 4870 2GB should be a lot (approximately 56%) faster with regards to anisotropic filtering than the Radeon HD 4790. (explain)
Pixel RateIf using lots of anti-aliasing is important to you, then the Radeon HD 4870 2GB is a better choice, by a large margin. (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.
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 maximum amount of information (in units of megabytes per second) that can be moved past the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory speed. In the case of DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.
Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.