Radeon HD 4870 2GB vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which features core speeds of 840 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 RAM. It features 800 SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Both cards have the same power consumption.

Memory Bandwidth

In theory, the Radeon HD 6790 should be a bit faster than the Radeon HD 4870 2GB overall. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 19200 (17%)

Texel Rate

The Radeon HD 6790 will be just a bit (about 12%) more effective at anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 3600 (12%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6790 is the winner, though not by far. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 1440 (12%)

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 maximum amount of information (measured in megabytes per second) that can be moved over the external memory interface in one second. It's worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. 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 texture map elements (texels) that are processed in one second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour 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 lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.