Radeon HD 4870 512MB vs Radeon HD 7790

Intro

Compare all of that to the Radeon HD 7790, which comes with a clock speed of 1000 MHz and a GDDR5 memory speed of 1500 MHz. It also uses a 128-bit memory bus, and uses a 28 nm design. It is made up of 896 SPUs, 56 TAUs, and 16 Raster Operation Units.

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

As far as performance goes, the Radeon HD 4870 512MB should theoretically be a bit superior to 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 is much (more or less 87%) faster with regards to texture 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 high levels of AA 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: Memory bandwidth is the largest amount of information (in units of MB per second) that can be transported past the external memory interface in a second. It is calculated by multiplying the card's interface width by its memory speed. In the case of DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The better 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 a second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.