Radeon HD 3850 256MB vs Radeon HD 4850 X2 512MB

Intro

Compare all that to the Radeon HD 4850 X2 512MB, which comes with a GPU core clock speed of 625 MHz, and 512 MB of GDDR3 RAM running at 993 MHz through a 256-bit bus. It also is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 175 Watts (233%)

Memory Bandwidth

Performance-wise, the Radeon HD 4850 X2 512MB should theoretically be much superior to the Radeon HD 3850 256MB overall. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 74112 (140%)

Texel Rate

The Radeon HD 4850 X2 512MB will be quite a bit (approximately 368%) faster with regards to AF than the Radeon HD 3850 256MB. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 39312 (368%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 4850 X2 512MB is superior to the Radeon HD 3850 256MB, and very much so. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
Radeon HD 3850 256MB		10688 Mpixels/sec
	Difference: 9312 (87%)

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 max amount of data (in units of MB per second) that can be transferred over the external memory interface in one second. It's calculated by multiplying the interface width by its memory clock speed. In the case of DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high 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 texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. 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 memory bandwidth is, the lower the ability to reach the maximum fill rate.