Radeon HD 4850 1GB vs Radeon HD 6850

Intro

Compare those specs to the Radeon HD 6850, which has clock speeds of 775 MHz on the GPU, and 1000 MHz on the 1024 MB of GDDR5 RAM. 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 4850 1GB		110 Watts
Radeon HD 6850		127 Watts
	Difference: 17 Watts (15%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6850 will be 101% quicker than the Radeon HD 4850 1GB overall, because of its greater bandwidth. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 64448 (101%)

Texel Rate

The Radeon HD 6850 is a lot (about 49%) more effective at texture filtering than the Radeon HD 4850 1GB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 4850 1GB		25000 Mtexels/sec
	Difference: 12200 (49%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 6850 is a better choice, by far. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4850 1GB		10000 Mpixels/sec
	Difference: 14800 (148%)

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 largest amount of information (in units of MB per second) that can be transported across the external memory interface in a second. It's worked out by multiplying the interface width by its memory speed. In the case of DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.