Radeon HD 4870 512MB vs Radeon HD 6870

Intro

Compare those specs to the Radeon HD 6870, which has GPU core speed of 900 MHz, and 1024 MB of GDDR5 memory set to run at 1050 MHz through a 256-bit bus. It also is comprised of 1120 SPUs, 56 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 512MB		150 Watts
Radeon HD 6870		151 Watts
	Difference: 1 Watts (1%)

Memory Bandwidth

As far as performance goes, the Radeon HD 6870 should in theory be a small bit superior to the Radeon HD 4870 512MB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 19200 (17%)

Texel Rate

The Radeon HD 6870 will be much (about 68%) faster with regards to AF than the Radeon HD 4870 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 20400 (68%)

Pixel Rate

The Radeon HD 6870 is much (approximately 140%) more effective at AA than the Radeon HD 4870 512MB, and also will be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 16800 (140%)

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 information (measured in MB per second) that can be moved past the external memory interface within a second. It is worked out by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total amount 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 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 card can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.