Radeon HD 4790 vs Radeon HD 4870 2GB

Intro

Compare those specifications to the Radeon HD 4870 2GB, which has a clock speed of 750 MHz and a GDDR5 memory speed of 900 MHz. It also uses a 256-bit memory bus, and makes use of a 55 nm design. It is comprised of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 4870 2GB should theoretically be a little bit superior to the Radeon HD 4790 in general. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 12800 (13%)

Texel Rate

The Radeon HD 4870 2GB is much (about 56%) more effective at AF than the Radeon HD 4790. (explain)

Radeon HD 4870 2GB		30000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 10800 (56%)

Pixel Rate

The Radeon HD 4870 2GB should be much (about 25%) more effective at AA than the Radeon HD 4790, and also capable of handling higher resolutions more effectively. (explain)

Radeon HD 4870 2GB		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 (counted in MB per second) that can be moved over the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. If the card has DDR memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, 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 amount of texture map elements (texels) that can be applied per second. This is calculated by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the video 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 the video card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.