Radeon HD 4870 2GB vs Radeon HD 7770

Intro

Compare all that to the Radeon HD 7770, which makes use of a 28 nm design. AMD has set the core speed at 1000 MHz. The GDDR5 memory runs at a frequency of 1125 MHz on this particular card. It features 640 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770		80 Watts
Radeon HD 4870 2GB		150 Watts
	Difference: 70 Watts (88%)

Memory Bandwidth

As far as performance goes, the Radeon HD 4870 2GB should theoretically be quite a bit superior to the Radeon HD 7770 overall. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon HD 7770 should be quite a bit (about 33%) more effective at anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 10000 (33%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 7770 is the winner, by far. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 4000 (33%)

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 megabytes per second) that can be moved past the external memory interface within a second. It is calculated by multiplying the interface width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed in one second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the 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 the graphics card can possibly record to its local memory in a 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 outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.