Radeon HD 4850 X2 1GB vs Radeon HD 7870

Intro

Compare that to the Radeon HD 7870, which comes with GPU core speed of 1000 MHz, and 2048 MB of GDDR5 RAM set to run at 1200 MHz through a 256-bit bus. It also is made up of 1280 SPUs, 80 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 75 Watts (43%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 will be 21% faster than the Radeon HD 4850 X2 1GB overall, due to its greater bandwidth. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 26496 (21%)

Texel Rate

The Radeon HD 7870 is much (approximately 60%) faster with regards to AF than the Radeon HD 4850 X2 1GB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4850 X2 1GB		50000 Mtexels/sec
	Difference: 30000 (60%)

Pixel Rate

The Radeon HD 7870 should be quite a bit (more or less 60%) better at AA than the Radeon HD 4850 X2 1GB, and able to handle higher resolutions more effectively. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4850 X2 1GB		20000 Mpixels/sec
	Difference: 12000 (60%)

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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of data (in units of megabytes per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the interface width by the speed of its memory. In the case of DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, 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 are processed per second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.