Radeon HD 4870 512MB vs Radeon HD 6750 1GB

Intro

Compare all of that to the Radeon HD 6750 1GB, which has a core clock frequency of 725 MHz and a GDDR5 memory speed of 1000 MHz. It also features a 128-bit bus, and uses a 40 nm design. It features 720 SPUs, 36 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6750 1GB		86 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 64 Watts (74%)

Memory Bandwidth

In theory, the Radeon HD 4870 512MB will be 80% quicker than the Radeon HD 6750 1GB overall, due to its greater bandwidth. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 6750 1GB		64000 MB/sec
	Difference: 51200 (80%)

Texel Rate

The Radeon HD 4870 512MB is a small bit (more or less 15%) more effective at texture filtering than the Radeon HD 6750 1GB. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
Radeon HD 6750 1GB		26100 Mtexels/sec
	Difference: 3900 (15%)

Pixel Rate

The Radeon HD 4870 512MB should be just a bit (about 3%) faster with regards to full screen anti-aliasing than the Radeon HD 6750 1GB, and will be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 4870 512MB		12000 Mpixels/sec
Radeon HD 6750 1GB		11600 Mpixels/sec
	Difference: 400 (3%)

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 (counted in megabytes per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied in one second. This number is calculated by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the card's 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 is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.