Compare any two graphics cards:
Radeon HD 7990 vs Radeon R9 290X
IntroThe Radeon HD 7990 has a GPU clock speed of 950 MHz, and the 3072 MB of GDDR5 RAM runs at 1500 MHz through a 384-bit bus. It also is comprised of 2048 Stream Processors, 128 TAUs, and 32 Raster Operation Units.
Compare those specs to the Radeon R9 290X, which has a core clock frequency of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also features a 512-bit memory bus, and makes use of a 28 nm design. It is made up of 2816 SPUs, 176 Texture Address Units, and 64 ROPs.
(No game benchmarks for this combination yet.)
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
In theory, the Radeon HD 7990 will be 80% faster than the Radeon R9 290X overall, because of its higher bandwidth. (explain)
Texel RateThe Radeon HD 7990 will be a lot (about 73%) faster with regards to AF than the Radeon R9 290X. (explain)
Pixel RateThe Radeon HD 7990 is a bit (approximately 19%) faster with regards to AA than the Radeon R9 290X, and will be capable of handling higher screen resolutions without losing too much performance. (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 max amount of data (measured in megabytes per second) that can be transported over the external memory interface in one second. The number is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.
Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.