Radeon HD 4870 1GB vs Radeon HD 7790

Intro

Compare all of that to the Radeon HD 7790, which comes with GPU core speed of 1000 MHz, and 1024 MB of GDDR5 memory set to run at 1500 MHz through a 128-bit bus. It also 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 1GB		150 Watts
	Difference: 65 Watts (76%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 1GB should be just a 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 will be much (about 87%) better at texture filtering 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

The Radeon HD 7790 is much (about 33%) more effective at full screen anti-aliasing than the Radeon HD 4870 1GB, and able to handle higher screen resolutions without losing too much performance. (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 data (counted in megabytes per second) that can be moved over the external memory interface in a second. It is calculated by multiplying the card's interface width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total texture units by the core speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.