Radeon HD 4890 2GB vs Radeon HD 7870

Intro

Compare those specifications to the Radeon HD 7870, which features core clock speeds of 1000 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 memory. 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 2GB		190 Watts
	Difference: 15 Watts (9%)

Memory Bandwidth

The Radeon HD 7870 should in theory perform quite a bit faster than the Radeon HD 4890 2GB overall. (explain)

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

Texel Rate

The Radeon HD 7870 should be quite a bit (approximately 100%) faster with regards to AF 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

If using a high resolution is important to you, then the Radeon HD 7870 is superior to the Radeon HD 4890 2GB, and very much so. (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 largest amount of data (in units of MB per second) that can be moved over the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. If it uses DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, 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 amount of texture map elements (texels) that are applied per second. This figure is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher this number, the better the graphics 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 most pixels the video card can 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 colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.