Radeon HD 4790 vs Radeon HD 4870 512MB

Intro

Compare those specifications to the Radeon HD 4870 512MB, which makes use of a 55 nm design. AMD has set the core frequency at 750 MHz. The GDDR5 memory is set to run at a frequency of 900 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 4870 512MB should theoretically be a bit superior to the Radeon HD 4790 overall. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 12800 (13%)

Texel Rate

The Radeon HD 4870 512MB is much (about 56%) better at AF than the Radeon HD 4790. (explain)

Radeon HD 4870 512MB		30000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 10800 (56%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 4870 512MB is superior to the Radeon HD 4790, by far. (explain)

Radeon HD 4870 512MB		12000 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 2400 (25%)

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 (measured in MB per second) that can be moved across the external memory interface within a second. The number is calculated by multiplying the card's bus width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The higher 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 figure is worked out by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.