Radeon HD 4790 vs Radeon HD 4870 512MB

Intro

Compare that 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 RAM works at a speed of 900 MHz on this card. It features 800(160x5) SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 4870 512MB will be 13% faster than the Radeon HD 4790 in general, because of its higher data rate. (explain)

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

Texel Rate

The Radeon HD 4870 512MB will be quite a bit (approximately 56%) better at anisotropic filtering 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 running with lots of anti-aliasing is important to you, then the Radeon HD 4870 512MB is the winner, and very much so. (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 max amount of information (in units of MB per second) that can be transferred over the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the better 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 number of texture map elements (texels) that are applied in one second. This is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the clock speed of the card. 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 many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.