Radeon HD 4850 X2 512MB vs Radeon HD 6790

Intro

Compare those specs to the Radeon HD 6790, which comes with core clock speeds of 840 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 memory. It features 800 SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6790		150 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 100 Watts (67%)

Memory Bandwidth

Performance-wise, the Radeon HD 6790 should in theory be a little bit superior to the Radeon HD 4850 X2 512MB overall. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 7296 (6%)

Texel Rate

The Radeon HD 4850 X2 512MB should be much (about 49%) faster with regards to texture filtering than the Radeon HD 6790. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 6790		33600 Mtexels/sec
	Difference: 16400 (49%)

Pixel Rate

The Radeon HD 4850 X2 512MB should be quite a bit (approximately 49%) more effective at full screen anti-aliasing than the Radeon HD 6790, and able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
Radeon HD 6790		13440 Mpixels/sec
	Difference: 6560 (49%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of data (measured in megabytes per second) that can be transported over the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.