GeForce 9800 GX2 vs Radeon HD 4890 2GB

Intro

Compare that to the Radeon HD 4890 2GB, which uses a 55 nm design. ATi has clocked the core speed at 1000 MHz. The GDDR5 RAM works at a frequency of 975 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 2GB		190 Watts
GeForce 9800 GX2		197 Watts
	Difference: 7 Watts (4%)

Memory Bandwidth

In theory, the GeForce 9800 GX2 is 3% faster than the Radeon HD 4890 2GB overall, due to its higher bandwidth. (explain)

GeForce 9800 GX2		128000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 3200 (3%)

Texel Rate

The GeForce 9800 GX2 should be quite a bit (more or less 92%) faster with regards to anisotropic filtering than the Radeon HD 4890 2GB. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 36800 (92%)

Pixel Rate

The GeForce 9800 GX2 should be just a bit (more or less 20%) faster with regards to anti-aliasing than the Radeon HD 4890 2GB, and should be capable of handling higher resolutions without losing too much performance. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 3200 (20%)

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 largest amount of information (counted in megabytes per second) that can be moved past the external memory interface in one second. The number is worked out by multiplying the bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total texture units of the card by the core clock 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 number of pixels the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core speed of the card. 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 fill rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.