Radeon HD 3870 512MB vs Radeon HD 7870

Intro

Compare all that to the Radeon HD 7870, which comes with a clock speed of 1000 MHz and a GDDR5 memory speed of 1200 MHz. It also makes use of a 256-bit memory bus, and makes use of a 28 nm design. It is comprised of 1280 SPUs, 80 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 512MB		106 Watts
Radeon HD 7870		175 Watts
	Difference: 69 Watts (65%)

Memory Bandwidth

In theory, the Radeon HD 7870 should be quite a bit faster than the Radeon HD 3870 512MB overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 3870 512MB		57600 MB/sec
	Difference: 96000 (167%)

Texel Rate

The Radeon HD 7870 should be quite a bit (approximately 545%) faster with regards to texture filtering than the Radeon HD 3870 512MB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 3870 512MB		12400 Mtexels/sec
	Difference: 67600 (545%)

Pixel Rate

The Radeon HD 7870 will be much (about 158%) better at FSAA than the Radeon HD 3870 512MB, and also should be able to handle higher resolutions better. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 3870 512MB		12400 Mpixels/sec
	Difference: 19600 (158%)

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: Bandwidth is the max amount of data (measured in MB per second) that can be transferred over the external memory interface in one second. It's worked out by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total number of texture units of the card by the core clock 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 applied per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs 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 also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.