Radeon HD 4870 1GB vs Radeon HD 7790

Intro

Compare those specs to the Radeon HD 7790, which comes with core speeds of 1000 MHz on the GPU, and 1500 MHz on the 1024 MB of GDDR5 memory. It features 896 SPUs as well as 56 TAUs and 16 Rasterization Operator 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

The Radeon HD 4870 1GB, in theory, should perform a small 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 is much (approximately 87%) faster with regards to anisotropic 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 will be a lot (about 33%) better at full screen anti-aliasing than the Radeon HD 4870 1GB, and also able to handle higher screen resolutions while still performing well. (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: Memory bandwidth is the largest amount of data (in units of MB per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the interface width by the speed of its memory. In the case of DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.