Radeon HD 4890 2GB vs Radeon HD 6870

Intro

Compare those specifications to the Radeon HD 6870, which uses a 40 nm design. AMD has clocked the core frequency at 900 MHz. The GDDR5 RAM is set to run at a frequency of 1050 MHz on this particular card. It features 1120 SPUs as well as 56 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6870		151 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 39 Watts (26%)

Memory Bandwidth

In theory, the Radeon HD 6870 should perform a little bit faster than the Radeon HD 4890 2GB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 9600 (8%)

Texel Rate

The Radeon HD 6870 should be quite a bit (about 26%) faster with regards to AF than the Radeon HD 4890 2GB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 10400 (26%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6870 is superior to the Radeon HD 4890 2GB, by a large margin. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4890 2GB		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 max amount of data (in units of MB per second) that can be transferred past the external memory interface within a second. It's calculated by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.