Radeon HD 4870 1GB vs Radeon HD 7790

Intro

Compare those specifications to the Radeon HD 7790, which comes with a clock frequency of 1000 MHz and a GDDR5 memory speed of 1500 MHz. It also features a 128-bit memory bus, and uses a 28 nm design. It features 896 SPUs, 56 Texture Address Units, 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 1GB		150 Watts
	Difference: 65 Watts (76%)

Memory Bandwidth

Theoretically, the Radeon HD 4870 1GB should perform a little bit faster than the Radeon HD 7790 in general. (explain)

Radeon HD 4870 1GB		115200 MB/sec
Radeon HD 7790		96000 MB/sec
	Difference: 19200 (20%)

Texel Rate

The Radeon HD 7790 should be a lot (approximately 87%) better at AF than the Radeon HD 4870 1GB. (explain)

Radeon HD 7790		56000 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 26000 (87%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 7790 is superior to the Radeon HD 4870 1GB, and very much so. (explain)

Radeon HD 7790		16000 Mpixels/sec
Radeon HD 4870 1GB		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 information (counted in MB per second) that can be transported past the external memory interface in one second. It is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per second. This 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 graphics 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 that the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.