Radeon HD 4890 2GB vs Radeon HD 7870

Intro

Compare those specifications to the Radeon HD 7870, which uses a 28 nm design. AMD has clocked the core speed at 1000 MHz. The GDDR5 RAM works at a frequency of 1200 MHz on this particular card. It features 1280 SPUs as well as 80 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 15 Watts (9%)

Memory Bandwidth

As far as performance goes, the Radeon HD 7870 should theoretically be a lot superior to the Radeon HD 4890 2GB in general. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 28800 (23%)

Texel Rate

The Radeon HD 7870 will be much (approximately 100%) better at texture filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 40000 (100%)

Pixel Rate

The Radeon HD 7870 will be a lot (about 100%) better at AA than the Radeon HD 4890 2GB, and will be able to handle higher resolutions more effectively. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4890 2GB		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 maximum amount of information (measured in MB per second) that can be transported across the external memory interface within a second. It's calculated by multiplying the bus width by the speed of its memory. If the card has DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.