Radeon HD 4890 1GB vs Radeon HD 7870

Intro

Compare all that to the Radeon HD 7870, which makes use of a 28 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 memory works at a frequency of 1200 MHz on this specific model. It features 1280 SPUs along with 80 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 15 Watts (9%)

Memory Bandwidth

In theory, the Radeon HD 7870 should perform a lot faster than the Radeon HD 4890 1GB in general. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 28800 (23%)

Texel Rate

The Radeon HD 7870 should be a lot (more or less 100%) faster with regards to anisotropic filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 40000 (100%)

Pixel Rate

The Radeon HD 7870 should be a lot (more or less 100%) better at full screen anti-aliasing than the Radeon HD 4890 1GB, and also should be able to handle higher screen resolutions better. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 16000 (100%)

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 max amount of data (counted in megabytes per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. In the case of DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen 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 amount of texture units of the card by the core clock speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the the core 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 is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.