Radeon HD 4870 2GB vs Radeon HD 5770

Intro

Compare all that to the Radeon HD 5770, which comes with a GPU core clock speed of 850 MHz, and 1024 MB of GDDR5 memory set to run at 1200 MHz through a 128-bit bus. It also features 800(160x5) Stream Processors, 40 TAUs, 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 2GB		150 Watts
	Difference: 42 Watts (39%)

Memory Bandwidth

The Radeon HD 4870 2GB should in theory perform a lot faster than the Radeon HD 5770 in general. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon HD 5770		76800 MB/sec
	Difference: 38400 (50%)

Texel Rate

The Radeon HD 5770 should be a little bit (more or less 13%) faster with regards to anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 5770		34000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 4000 (13%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 5770 is a better choice, though only just barely. (explain)

Radeon HD 5770		13600 Mpixels/sec
Radeon HD 4870 2GB		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 largest amount of information (counted in MB per second) that can be transported over the external memory interface in a second. The number is worked out by multiplying the bus width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better 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 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 maximum amount of pixels that the graphics chip could possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.