Radeon HD 4890 1GB vs Radeon HD 6870

Intro

Compare all of that to the Radeon HD 6870, which comes with GPU clock speed of 900 MHz, and 1024 MB of GDDR5 memory set to run at 1050 MHz through a 256-bit bus. It also is made up of 1120 Stream Processors, 56 TAUs, and 32 Raster Operation Units.

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

Performance-wise, the Radeon HD 6870 should theoretically be a small bit superior to 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 (more or less 26%) more effective at AF 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 will be quite a bit (approximately 80%) faster with regards to full screen anti-aliasing than the Radeon HD 4890 1GB, and able to handle higher resolutions while still performing well. (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 max amount of information (counted in MB per second) that can be moved across the external memory interface in one second. It is worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the 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 texture map elements (texels) that can be applied per second. This number is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the clock 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 rate also depends 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 max fill rate.