Radeon HD 3850 X2 vs Radeon HD 4850 512MB

Intro

Compare that to the Radeon HD 4850 512MB, which features core clock speeds of 625 MHz on the GPU, and 993 MHz on the 512 MB of GDDR3 RAM. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 3850 X2, in theory, should perform quite a bit faster than the Radeon HD 4850 512MB in general. (explain)

Radeon HD 3850 X2		105984 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 42432 (67%)

Texel Rate

The Radeon HD 4850 512MB should be a small bit (approximately 17%) more effective at texture filtering than the Radeon HD 3850 X2. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 3624 (17%)

Pixel Rate

The Radeon HD 3850 X2 should be quite a bit (more or less 114%) better at anti-aliasing than the Radeon HD 4850 512MB, and also should be capable of handling higher resolutions better. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 11376 (114%)

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 largest amount of information (in units of megabytes per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the interface width by its memory speed. If it uses DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster 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 are applied per second. This is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few 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.