Radeon HD 3870 1GB vs Radeon HD 4850 X2 512MB

Intro

Compare that to the Radeon HD 4850 X2 512MB, which makes use of a 55 nm design. AMD has set the core speed at 625 MHz. The GDDR3 memory is set to run at a speed of 993 MHz on this specific card. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3870 1GB		106 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 144 Watts (136%)

Memory Bandwidth

The Radeon HD 4850 X2 512MB, in theory, should perform much faster than the Radeon HD 3870 1GB overall. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
Radeon HD 3870 1GB		72000 MB/sec
	Difference: 55104 (77%)

Texel Rate

The Radeon HD 4850 X2 512MB is much (approximately 303%) faster with regards to AF than the Radeon HD 3870 1GB. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 37600 (303%)

Pixel Rate

The Radeon HD 4850 X2 512MB is a lot (about 61%) better at full screen anti-aliasing than the Radeon HD 3870 1GB, and will be capable of handling higher screen resolutions better. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 7600 (61%)

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 maximum amount of information (measured in MB per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the bus width by the speed of its memory. If it uses DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's 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 processed per second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour 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 rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.