Radeon HD 4870 512MB vs Radeon HD 7870

Intro

Compare those specs to the Radeon HD 7870, which uses a 28 nm design. AMD has clocked the core frequency at 1000 MHz. The GDDR5 RAM is set to run at a speed of 1200 MHz on this specific model. It features 1280 SPUs as well as 80 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 512MB		150 Watts
Radeon HD 7870		175 Watts
	Difference: 25 Watts (17%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7870 is 33% faster than the Radeon HD 4870 512MB overall, due to its higher data rate. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 38400 (33%)

Texel Rate

The Radeon HD 7870 is much (approximately 167%) more effective at texture filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 50000 (167%)

Pixel Rate

The Radeon HD 7870 will be much (approximately 167%) more effective at FSAA than the Radeon HD 4870 512MB, and able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 20000 (167%)

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 across the external memory interface within a second. It's calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR type RAM, it 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 high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This is calculated by multiplying the total amount of texture units 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. 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 many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.