GeForce GTX 275 vs Radeon HD 4890 1GB

Intro

Compare those specifications 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 uses a 55 nm design. It is made up of 800(160x5) SPUs, 40 Texture Address Units, 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 GTX 275		219 Watts
	Difference: 29 Watts (15%)

Memory Bandwidth

The GeForce GTX 275, in theory, should be a little bit faster than the Radeon HD 4890 1GB in general. (explain)

GeForce GTX 275		127008 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 2208 (2%)

Texel Rate

The GeForce GTX 275 will be much (approximately 27%) better at anisotropic filtering than the Radeon HD 4890 1GB. (explain)

GeForce GTX 275		50640 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 10640 (27%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce GTX 275 is superior to the Radeon HD 4890 1GB, but not by far. (explain)

GeForce GTX 275		17724 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 1724 (11%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of data (measured in megabytes per second) that can be moved across the external memory interface within a second. The number is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out 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 drawing the pixels (image) on the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.