Radeon HD 4850 X2 512MB vs Radeon HD 4870 X2

Intro

Compare all of that to the Radeon HD 4870 X2, which has a GPU core clock speed of 750 MHz, and 1024 MB of GDDR5 memory running at 900 MHz through a 256-bit bus. It also is made up of 800(160x5) Stream Processors, 40 TAUs, and 16 ROPs.

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

The Radeon HD 4870 X2, in theory, should be much faster than the Radeon HD 4850 X2 512MB overall. (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 is a small bit (more or less 20%) more effective 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

The Radeon HD 4870 X2 will be a little bit (more or less 20%) better at anti-aliasing than the Radeon HD 4850 X2 512MB, and also will be able to handle higher screen resolutions while still performing well. (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 largest amount of data (measured in megabytes per second) that can be transferred over the external memory interface in a second. The number is worked out by multiplying the bus width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.