Radeon HD 4850 X2 512MB vs Radeon HD 4870 X2

Intro

Compare those specs to the Radeon HD 4870 X2, which uses a 55 nm design. AMD has set the core speed at 750 MHz. The GDDR5 RAM works at a frequency of 900 MHz on this card. It features 800(160x5) SPUs as well as 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 X2 512MB		250 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 100 Watts (40%)

Memory Bandwidth

Performance-wise, the Radeon HD 4870 X2 should in theory be quite a bit better than the Radeon HD 4850 X2 512MB in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 4850 X2 512MB		127104 MB/sec
	Difference: 103296 (81%)

Texel Rate

The Radeon HD 4870 X2 should be a bit (approximately 20%) better at AF than the Radeon HD 4850 X2 512MB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 4850 X2 512MB		50000 Mtexels/sec
	Difference: 10000 (20%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 4870 X2 is a better choice, but only just. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 4850 X2 512MB		20000 Mpixels/sec
	Difference: 4000 (20%)

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: Bandwidth is the maximum amount of information (counted in megabytes per second) that can be transported over the external memory interface in a second. It's calculated by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one 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 higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most 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 amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka 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 maximum fill rate.