GeForce 9800 GX2 vs Radeon HD 4890 1GB

Intro

Compare those specs to the Radeon HD 4890 1GB, which comes with a clock frequency of 1000 MHz and a GDDR5 memory frequency of 975 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 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
GeForce 9800 GX2		197 Watts
	Difference: 7 Watts (4%)

Memory Bandwidth

Theoretically speaking, the GeForce 9800 GX2 will be 3% faster than the Radeon HD 4890 1GB in general, due to its higher data rate. (explain)

GeForce 9800 GX2		128000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 3200 (3%)

Texel Rate

The GeForce 9800 GX2 should be much (about 92%) more effective at AF than the Radeon HD 4890 1GB. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 36800 (92%)

Pixel Rate

The GeForce 9800 GX2 should be a bit (about 20%) faster with regards to full screen anti-aliasing than the Radeon HD 4890 1GB, and should be capable of handling higher screen resolutions while still performing well. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
Radeon HD 4890 1GB		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: Memory bandwidth is the maximum amount of data (counted in MB per second) that can be transported across the external memory interface within a second. The number is worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better 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 texture map elements (texels) that can be processed per second. This number is worked out by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the graphics 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 maximum number of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.