Radeon HD 4850 512MB vs Radeon HD 4870 512MB

Intro

Compare all that to the Radeon HD 4870 512MB, which makes use of a 55 nm design. AMD has clocked the core speed at 750 MHz. The GDDR5 memory works at a frequency of 900 MHz on this specific card. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 512MB		110 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 40 Watts (36%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 512MB should be 81% quicker than the Radeon HD 4850 512MB in general, due to its greater bandwidth. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 51648 (81%)

Texel Rate

The Radeon HD 4870 512MB is a bit (approximately 20%) faster with regards to texture filtering than the Radeon HD 4850 512MB. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 5000 (20%)

Pixel Rate

The Radeon HD 4870 512MB will be a bit (more or less 20%) more effective at full screen anti-aliasing than the Radeon HD 4850 512MB, and should be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 4870 512MB		12000 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 2000 (20%)

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 largest amount of data (in units of MB per second) that can be transported past the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory speed. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster 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 can be processed per second. This is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.