Radeon HD 4890 1GB vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which makes use of a 40 nm design. AMD has set the core speed at 775 MHz. The GDDR5 RAM works at a speed of 1000 MHz on this specific card. It features 960 SPUs as well as 48 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850		127 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 63 Watts (50%)

Memory Bandwidth

As far as performance goes, the Radeon HD 6850 should theoretically be a bit superior to the Radeon HD 4890 1GB overall. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 3200 (3%)

Texel Rate

The Radeon HD 4890 1GB will be a bit (about 8%) more effective at texture filtering than the Radeon HD 6850. (explain)

Radeon HD 4890 1GB		40000 Mtexels/sec
Radeon HD 6850		37200 Mtexels/sec
	Difference: 2800 (8%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 6850 is a better choice, and very much so. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 8800 (55%)

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 data (in units of megabytes per second) that can be moved over the external memory interface in one second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's 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 amount of texture map elements (texels) that can be applied 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 in a second.

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