Radeon HD 4790 vs Radeon HD 7870

Intro

Compare those specs to the Radeon HD 7870, which features core clock speeds of 1000 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 RAM. It features 1280 SPUs along with 80 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 7870, in theory, should perform much faster than the Radeon HD 4790 in general. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 51200 (50%)

Texel Rate

The Radeon HD 7870 will be much (about 317%) more effective at AF than the Radeon HD 4790. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 60800 (317%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 7870 is a better choice, by a large margin. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 22400 (233%)

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 (counted in megabytes per second) that can be moved over the external memory interface in a second. It's calculated by multiplying the card's interface width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, 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 texture map elements (texels) that can be applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka 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 of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.