Radeon HD 4870 1GB vs Radeon HD 7770

Intro

Compare all of that to the Radeon HD 7770, which comes with GPU clock speed of 1000 MHz, and 1024 MB of GDDR5 RAM running at 1125 MHz through a 128-bit bus. It also is comprised of 640 SPUs, 40 TAUs, 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 1GB		150 Watts
	Difference: 70 Watts (88%)

Memory Bandwidth

In theory, the Radeon HD 4870 1GB should perform much faster than the Radeon HD 7770 in general. (explain)

Radeon HD 4870 1GB		115200 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon HD 7770 should be quite a bit (more or less 33%) better at texture filtering than the Radeon HD 4870 1GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 10000 (33%)

Pixel Rate

The Radeon HD 7770 should be much (more or less 33%) better at AA than the Radeon HD 4870 1GB, and also able to handle higher resolutions while still performing well. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4870 1GB		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 max amount of data (counted in MB per second) that can be transferred past the external memory interface in one second. The number is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the 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 amount of texture map elements (texels) that are applied per second. This is calculated 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 card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the clock speed of the card. 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 also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.