Radeon HD 4850 X2 1GB vs Radeon HD 4890 1GB

Intro

Compare that to the Radeon HD 4890 1GB, which uses a 55 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 RAM runs at a frequency of 975 MHz on this card. It features 800(160x5) SPUs along with 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 1GB		190 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 60 Watts (32%)

Memory Bandwidth

Performance-wise, the Radeon HD 4850 X2 1GB should in theory be just a bit superior to the Radeon HD 4890 1GB in general. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 2304 (2%)

Texel Rate

The Radeon HD 4850 X2 1GB is quite a bit (more or less 25%) faster with regards to texture filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 10000 (25%)

Pixel Rate

The Radeon HD 4850 X2 1GB should be a lot (more or less 25%) better at anti-aliasing than the Radeon HD 4890 1GB, and should be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 4000 (25%)

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 (counted in MB per second) that can be moved past the external memory interface in one second. The number is worked out by multiplying the card's bus width by its memory speed. If the card has DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out 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 drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.