Radeon HD 4870 1GB vs Radeon HD 5770

Intro

Compare those specifications to the Radeon HD 5770, which uses a 40 nm design. AMD has set the core speed at 850 MHz. The GDDR5 memory runs at a speed of 1200 MHz on this specific model. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 5770		108 Watts
Radeon HD 4870 1GB		150 Watts
	Difference: 42 Watts (39%)

Memory Bandwidth

The Radeon HD 4870 1GB should theoretically perform much faster than the Radeon HD 5770 overall. (explain)

Radeon HD 4870 1GB		115200 MB/sec
Radeon HD 5770		76800 MB/sec
	Difference: 38400 (50%)

Texel Rate

The Radeon HD 5770 should be a small bit (more or less 13%) more effective at texture filtering than the Radeon HD 4870 1GB. (explain)

Radeon HD 5770		34000 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 4000 (13%)

Pixel Rate

The Radeon HD 5770 is a little bit (approximately 13%) more effective at AA than the Radeon HD 4870 1GB, and also able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 5770		13600 Mpixels/sec
Radeon HD 4870 1GB		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 information (measured in megabytes per second) that can be transported across the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better 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 texture map elements (texels) that can be applied in one second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.