Radeon HD 4850 X2 1GB vs Radeon HD 4870 X2

Intro

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

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 X2 1GB		250 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 100 Watts (40%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should be 81% quicker than the Radeon HD 4850 X2 1GB overall, due to its greater data rate. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 4850 X2 1GB		127104 MB/sec
	Difference: 103296 (81%)

Texel Rate

The Radeon HD 4870 X2 will be a bit (about 20%) better at AF than the Radeon HD 4850 X2 1GB. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 4850 X2 1GB		50000 Mtexels/sec
	Difference: 10000 (20%)

Pixel Rate

The Radeon HD 4870 X2 should be a small bit (more or less 20%) better at full screen anti-aliasing than the Radeon HD 4850 X2 1GB, and will be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon HD 4850 X2 1GB		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 largest amount of data (measured in megabytes per second) that can be transported across the external memory interface within a second. The number is calculated by multiplying the bus width by the speed of its memory. If the card has DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This number is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.