Radeon HD 3870 1GB vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which features a clock frequency of 840 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 256-bit bus, and uses a 40 nm design. It is comprised of 800 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 1GB		106 Watts
Radeon HD 6790		150 Watts
	Difference: 44 Watts (42%)

Memory Bandwidth

In theory, the Radeon HD 6790 should perform quite a bit faster than the Radeon HD 3870 1GB in general. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 3870 1GB		72000 MB/sec
	Difference: 62400 (87%)

Texel Rate

The Radeon HD 6790 should be quite a bit (approximately 171%) more effective at AF than the Radeon HD 3870 1GB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 21200 (171%)

Pixel Rate

The Radeon HD 6790 is a bit (approximately 8%) better at anti-aliasing than the Radeon HD 3870 1GB, and will be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 1040 (8%)

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 data (measured in MB per second) that can be moved across the external memory interface within a second. It's calculated by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This number 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.