Radeon HD 4830 1GB vs Radeon HD 4850 X2 1GB

Intro

Compare all that to the Radeon HD 4850 X2 1GB, which features a clock speed of 625 MHz and a GDDR3 memory frequency of 993 MHz. It also features a 256-bit bus, and uses a 55 nm design. It is comprised of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4830 1GB		95 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 155 Watts (163%)

Memory Bandwidth

In theory, the Radeon HD 4850 X2 1GB should perform much faster than the Radeon HD 4830 1GB overall. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 4830 1GB		57600 MB/sec
	Difference: 69504 (121%)

Texel Rate

The Radeon HD 4850 X2 1GB should be much (about 172%) more effective at texture filtering than the Radeon HD 4830 1GB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 4830 1GB		18400 Mtexels/sec
	Difference: 31600 (172%)

Pixel Rate

The Radeon HD 4850 X2 1GB should be a lot (more or less 117%) more effective at AA than the Radeon HD 4830 1GB, and also should be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 4830 1GB		9200 Mpixels/sec
	Difference: 10800 (117%)

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 largest amount of data (counted in megabytes per second) that can be transferred past the external memory interface in one second. It is worked out by multiplying the card's interface width by its memory clock speed. If it uses DDR RAM, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better this number, the better the graphics 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 most pixels the video card can possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number 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 filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.