Compare any two graphics cards:
Radeon HD 4870 512MB vs Radeon HD 7850
IntroThe Radeon HD 4870 512MB comes with clock speeds of 750 MHz on the GPU, and 900 MHz on the 512 MB of GDDR5 RAM. It features 800(160x5) SPUs along with 40 TAUs and 16 ROPs.
Compare those specs to the Radeon HD 7850, which has core speeds of 860 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 RAM. It features 1024 SPUs as well as 64 Texture Address Units and 32 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
As far as performance goes, the Radeon HD 7850 should theoretically be much superior to the Radeon HD 4870 512MB in general. (explain)
Texel RateThe Radeon HD 7850 is much (about 83%) faster with regards to anisotropic filtering than the Radeon HD 4870 512MB. (explain)
Pixel RateThe Radeon HD 7850 should be much (about 129%) faster with regards to full screen anti-aliasing than the Radeon HD 4870 512MB, and also should be capable of handling higher resolutions while still performing well. (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: Bandwidth is the maximum amount of data (in units of MB per second) that can be moved across the external memory interface in a second. The number is calculated by multiplying the interface width by the speed of its memory. If it uses DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total number of texture units by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.
Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.