Radeon HD 4870 512MB vs Radeon HD 7790

Intro

Compare those specifications to the Radeon HD 7790, which has a core clock frequency of 1000 MHz and a GDDR5 memory speed of 1500 MHz. It also features a 128-bit bus, and makes use of a 28 nm design. It is comprised 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

In theory, the Radeon HD 4870 512MB is 20% faster than the Radeon HD 7790 overall, because of its higher data rate. (explain)

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

Texel Rate

The Radeon HD 7790 is a lot (about 87%) more effective at AF 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

The Radeon HD 7790 will be a lot (about 33%) more effective at full screen anti-aliasing than the Radeon HD 4870 512MB, and also will be capable of handling higher resolutions while still performing well. (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 maximum amount of data (in units of megabytes per second) that can be transported over the external memory interface within a second. It is calculated by multiplying the bus width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could 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 ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.