Radeon HD 5870 vs Radeon HD 7870

Intro

Compare all that to the Radeon HD 7870, which features a core clock speed of 1000 MHz and a GDDR5 memory frequency of 1200 MHz. It also makes use of a 256-bit bus, and uses a 28 nm design. It is comprised of 1280 SPUs, 80 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
Radeon HD 5870		188 Watts
	Difference: 13 Watts (7%)

Memory Bandwidth

Both cards have exactly the same memory bandwidth, so theoretically they should have identical performance. (explain)

Texel Rate

The Radeon HD 7870 is a bit (approximately 18%) more effective at AF than the Radeon HD 5870. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 5870		68000 Mtexels/sec
	Difference: 12000 (18%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 7870 is a better choice, though only just barely. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 5870		27200 Mpixels/sec
	Difference: 4800 (18%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of data (in units of megabytes per second) that can be transported across the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If the card has DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated 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 outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few 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.