Radeon HD 4790 vs Radeon HD 4850 X2 1GB

Intro

Compare those specifications to the Radeon HD 4850 X2 1GB, which features a clock frequency of 625 MHz and a GDDR3 memory speed of 993 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 4850 X2 1GB should perform a lot faster than the Radeon HD 4790 in general. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 24704 (24%)

Texel Rate

The Radeon HD 4850 X2 1GB will be a lot (approximately 160%) faster with regards to texture filtering than the Radeon HD 4790. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 30800 (160%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 4850 X2 1GB is superior to the Radeon HD 4790, by a large margin. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 10400 (108%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of information (in units of MB per second) that can be transported over the external memory interface within a second. It is worked out by multiplying the bus width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, 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 figure is worked out by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output 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 potential to reach the maximum fill rate.