Radeon HD 4650 512MB vs Radeon HD 6870

Intro

Compare all that to the Radeon HD 6870, which features core speeds of 900 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 memory. It features 1120 SPUs as well as 56 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 6870		151 Watts
	Difference: 96 Watts (175%)

Memory Bandwidth

The Radeon HD 6870, in theory, should perform much faster than the Radeon HD 4650 512MB overall. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 118400 (740%)

Texel Rate

The Radeon HD 6870 will be quite a bit (about 163%) more effective at anisotropic filtering than the Radeon HD 4650 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 31200 (163%)

Pixel Rate

The Radeon HD 6870 should be quite a bit (about 500%) better at AA than the Radeon HD 4650 512MB, and should be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 24000 (500%)

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 (counted in megabytes per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher 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 number of texture map elements (texels) that are processed in one second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip 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 number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.