Radeon HD 4790 vs Radeon HD 6850

Intro

Compare that to the Radeon HD 6850, which makes use of a 40 nm design. AMD has clocked the core frequency at 775 MHz. The GDDR5 memory runs at a frequency of 1000 MHz on this specific card. It features 960 SPUs along with 48 Texture Address Units and 32 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically, the Radeon HD 6850 should be quite a bit faster than the Radeon HD 4790 overall. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 25600 (25%)

Texel Rate

The Radeon HD 6850 should be a lot (approximately 94%) better at texture filtering than the Radeon HD 4790. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 18000 (94%)

Pixel Rate

The Radeon HD 6850 is much (about 158%) more effective at full screen anti-aliasing than the Radeon HD 4790, and also capable of handling higher resolutions more effectively. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 15200 (158%)

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 information (measured in megabytes per second) that can be transferred over the external memory interface in one second. It's worked out by multiplying the bus width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This is worked out by multiplying the total texture units of the card by the core clock speed of the chip. The better this number, the better the 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 most pixels that the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.