Radeon HD 4830 512MB vs Radeon HD 4870 1GB

Intro

Compare that to the Radeon HD 4870 1GB, which comes with clock speeds of 750 MHz on the GPU, and 900 MHz on the 1024 MB of GDDR5 memory. It features 800(160x5) SPUs as well as 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4830 512MB		95 Watts
Radeon HD 4870 1GB		150 Watts
	Difference: 55 Watts (58%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 1GB will be 100% quicker than the Radeon HD 4830 512MB in general, due to its greater data rate. (explain)

Radeon HD 4870 1GB		115200 MB/sec
Radeon HD 4830 512MB		57600 MB/sec
	Difference: 57600 (100%)

Texel Rate

The Radeon HD 4870 1GB is quite a bit (more or less 63%) more effective at texture filtering than the Radeon HD 4830 512MB. (explain)

Radeon HD 4870 1GB		30000 Mtexels/sec
Radeon HD 4830 512MB		18400 Mtexels/sec
	Difference: 11600 (63%)

Pixel Rate

The Radeon HD 4870 1GB should be quite a bit (more or less 30%) better at FSAA than the Radeon HD 4830 512MB, and able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 4870 1GB		12000 Mpixels/sec
Radeon HD 4830 512MB		9200 Mpixels/sec
	Difference: 2800 (30%)

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 maximum amount of information (counted in megabytes per second) that can be moved across the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. In the case of DDR type RAM, it should be multiplied by 2 once again. If it uses 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, High Dynamic Range and high resolutions.

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

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