Radeon HD 4870 512MB vs Radeon HD 5770

Intro

Compare all that to the Radeon HD 5770, which comes with a core clock speed of 850 MHz and a GDDR5 memory speed of 1200 MHz. It also makes use of a 128-bit memory bus, and makes use of a 40 nm design. It is made up of 800(160x5) SPUs, 40 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 5770		108 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 42 Watts (39%)

Memory Bandwidth

The Radeon HD 4870 512MB should in theory perform quite a bit faster than the Radeon HD 5770 overall. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 5770		76800 MB/sec
	Difference: 38400 (50%)

Texel Rate

The Radeon HD 5770 is a little bit (approximately 13%) better at texture filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 5770		34000 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 4000 (13%)

Pixel Rate

The Radeon HD 5770 should be just a bit (more or less 13%) more effective at AA than the Radeon HD 4870 512MB, and also will be capable of handling higher screen resolutions more effectively. (explain)

Radeon HD 5770		13600 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 1600 (13%)

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 maximum amount of data (in units of megabytes per second) that can be transferred over the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If the card has DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs 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 fill rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.