Radeon HD 7870 XT vs Radeon HD 7950 3GB

Intro

Compare those specifications to the Radeon HD 7950 3GB, which features a core clock frequency of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also uses a 384-bit memory bus, and makes use of a 28 nm design. It features 1792 SPUs, 112 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870 XT		185 Watts
Radeon HD 7950 3GB		200 Watts
	Difference: 15 Watts (8%)

Memory Bandwidth

In theory, the Radeon HD 7950 3GB will be 25% quicker than the Radeon HD 7870 XT in general, due to its higher data rate. (explain)

Radeon HD 7950 3GB		240000 MB/sec
Radeon HD 7870 XT		192000 MB/sec
	Difference: 48000 (25%)

Texel Rate

The Radeon HD 7950 3GB should be a small bit (approximately 1%) more effective at anisotropic filtering than the Radeon HD 7870 XT. (explain)

Radeon HD 7950 3GB		89600 Mtexels/sec
Radeon HD 7870 XT		88800 Mtexels/sec
	Difference: 800 (1%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7870 XT is a better choice, but not by far. (explain)

Radeon HD 7870 XT		29600 Mpixels/sec
Radeon HD 7950 3GB		25600 Mpixels/sec
	Difference: 4000 (16%)

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 maximum amount of information (in units of megabytes per second) that can be moved past the external memory interface in one second. It is worked out by multiplying the card's interface width by the speed of its memory. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster 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 can be applied per second. This number is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. The number 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 outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.