Radeon HD 4870 512MB vs Radeon HD 7790

Intro

Compare those specifications to the Radeon HD 7790, which makes use of a 28 nm design. AMD has clocked the core speed at 1000 MHz. The GDDR5 RAM is set to run at a frequency of 1500 MHz on this specific card. It features 896 SPUs as well as 56 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7790		85 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 65 Watts (76%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 512MB should theoretically be a little bit better than the Radeon HD 7790 in general. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 7790		96000 MB/sec
	Difference: 19200 (20%)

Texel Rate

The Radeon HD 7790 should be a lot (more or less 87%) faster with regards to anisotropic filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 7790		56000 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 26000 (87%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7790 is a better choice, by a large margin. (explain)

Radeon HD 7790		16000 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 4000 (33%)

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 max amount of data (counted in MB per second) that can be transported over the external memory interface within a second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If 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 higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics 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 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 calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.