Radeon HD 3850 X2 vs Radeon HD 4890 1GB

Intro

Compare that to the Radeon HD 4890 1GB, which features a core clock frequency of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also makes use of a 256-bit bus, and uses a 55 nm design. It features 800(160x5) SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 4890 1GB should theoretically be a little bit superior to the Radeon HD 3850 X2 overall. (explain)

Radeon HD 4890 1GB		124800 MB/sec
Radeon HD 3850 X2		105984 MB/sec
	Difference: 18816 (18%)

Texel Rate

The Radeon HD 4890 1GB is much (about 87%) faster with regards to AF than the Radeon HD 3850 X2. (explain)

Radeon HD 4890 1GB		40000 Mtexels/sec
Radeon HD 3850 X2		21376 Mtexels/sec
	Difference: 18624 (87%)

Pixel Rate

The Radeon HD 3850 X2 is much (approximately 34%) more effective at AA than the Radeon HD 4890 1GB, and capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 3850 X2		21376 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 5376 (34%)

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 data (in units of MB per second) that can be transferred past the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, 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 are processed in one second. This figure is calculated by multiplying the total number of texture units by the core clock speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels the video 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 amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.