Radeon HD 4870 1GB vs Radeon HD 7790

Intro

Compare all that 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 RAM. It features 896 SPUs as well as 56 Texture Address Units 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

Theoretically speaking, the Radeon HD 4870 1GB will be 20% quicker than the Radeon HD 7790 overall, due to its greater bandwidth. (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 a lot (about 87%) more effective 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

If running with a high screen resolution 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: Memory bandwidth is the largest amount of information (measured in MB per second) that can be transported across the external memory interface within a second. The number is worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher 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 number of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total 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 processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to the local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.