Radeon HD 3850 X2 vs Radeon HD 4850 1GB

Intro

Compare those specifications to the Radeon HD 4850 1GB, which features a core clock speed of 625 MHz and a GDDR4 memory frequency of 993 MHz. It also uses a 256-bit bus, and uses a 55 nm design. It features 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 3850 X2 should in theory be much better than the Radeon HD 4850 1GB overall. (explain)

Radeon HD 3850 X2		105984 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 42432 (67%)

Texel Rate

The Radeon HD 4850 1GB should be a bit (approximately 17%) better at AF than the Radeon HD 3850 X2. (explain)

Radeon HD 4850 1GB		25000 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 3624 (17%)

Pixel Rate

The Radeon HD 3850 X2 should be much (about 114%) better at AA than the Radeon HD 4850 1GB, and also capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
Radeon HD 4850 1GB		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 maximum amount of information (measured in MB per second) that can be transported over the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs 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 lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.