Radeon HD 4890 1GB vs Radeon HD 6870

Intro

Compare all that to the Radeon HD 6870, which uses a 40 nm design. AMD has clocked the core frequency at 900 MHz. The GDDR5 RAM runs at a speed of 1050 MHz on this particular model. It features 1120 SPUs along with 56 Texture Address Units 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 little 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 is quite a bit (about 26%) more effective at texture 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

If using lots of anti-aliasing is important to you, then the Radeon HD 6870 is the winner, by far. (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: Bandwidth is the maximum amount of data (measured in MB per second) that can be moved past the external memory interface in one second. The number is calculated by multiplying the interface width by the speed of its memory. In the case of DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the core clock speed. 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 also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.