Radeon HD 4890 1GB vs Radeon HD 6870

Intro

Compare that to the Radeon HD 6870, which features a core clock frequency of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also makes use of a 256-bit bus, and uses a 40 nm design. It features 1120 SPUs, 56 TAUs, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6870		151 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 39 Watts (26%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6870 should be a small bit faster than the Radeon HD 4890 1GB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 9600 (8%)

Texel Rate

The Radeon HD 6870 will be much (approximately 26%) faster with regards to anisotropic filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 10400 (26%)

Pixel Rate

The Radeon HD 6870 should be much (about 80%) faster with regards to FSAA than the Radeon HD 4890 1GB, and also should be able to handle higher screen resolutions better. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 12800 (80%)

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 transported past the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR memory, it must be multiplied by 2 once again. If 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 amount of texture map elements (texels) that are processed in one second. This number is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better the texel rate, the better the video 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 maximum number of pixels that the graphics chip could possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant 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 maximum fill rate.