Radeon HD 4870 1GB vs Radeon HD 6950 2GB

Intro

Compare all of that to the Radeon HD 6950 2GB, which uses a 40 nm design. AMD has set the core speed at 800 MHz. The GDDR5 RAM is set to run at a speed of 1250 MHz on this specific model. It features 1408 SPUs as well as 88 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 1GB		150 Watts
Radeon HD 6950 2GB		200 Watts
	Difference: 50 Watts (33%)

Memory Bandwidth

As far as performance goes, the Radeon HD 6950 2GB should in theory be quite a bit better than the Radeon HD 4870 1GB overall. (explain)

Radeon HD 6950 2GB		160000 MB/sec
Radeon HD 4870 1GB		115200 MB/sec
	Difference: 44800 (39%)

Texel Rate

The Radeon HD 6950 2GB is quite a bit (approximately 135%) more effective at AF than the Radeon HD 4870 1GB. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 40400 (135%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6950 2GB is superior to the Radeon HD 4870 1GB, by far. (explain)

Radeon HD 6950 2GB		25600 Mpixels/sec
Radeon HD 4870 1GB		12000 Mpixels/sec
	Difference: 13600 (113%)

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 largest amount of data (counted in MB per second) that can be transported across the external memory interface in one second. It's calculated by multiplying the interface width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines 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 output rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.