Compare any two graphics cards:
Radeon HD 6770 1GB vs Radeon HD 6870
IntroThe Radeon HD 6770 1GB has a GPU clock speed of 900 MHz, and the 1024 MB of GDDR5 RAM runs at 1050 MHz through a 128-bit bus. It also features 800 Stream Processors, 40 TAUs, and 16 Raster Operation Units.
Compare all that to the Radeon HD 6870, which has a clock frequency of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also makes use of a 256-bit memory bus, and uses a 40 nm design. It features 1120 SPUs, 56 Texture Address Units, and 32 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
The Radeon HD 6870 should in theory be quite a bit faster than the Radeon HD 6770 1GB in general. (explain)
Texel RateThe Radeon HD 6870 will be a lot (more or less 40%) more effective at texture filtering than the Radeon HD 6770 1GB. (explain)
Pixel RateThe Radeon HD 6870 will be a lot (approximately 100%) better at full screen anti-aliasing than the Radeon HD 6770 1GB, and also should be able to handle higher resolutions more effectively. (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 data (in units of megabytes per second) that can be transported over the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's 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 amount of texture map elements (texels) that can be applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better this number, 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 graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.