GeForce GTX 275 vs Radeon HD 4890 1GB

Intro

Compare those specifications to the Radeon HD 4890 1GB, which comes with GPU clock speed of 1000 MHz, and 1024 MB of GDDR5 RAM running at 975 MHz through a 256-bit bus. It also is comprised of 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

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

In theory, the GeForce GTX 275 should perform a little bit faster than the Radeon HD 4890 1GB overall. (explain)

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

Texel Rate

The GeForce GTX 275 should be quite a bit (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

The GeForce GTX 275 should be a small bit (more or less 11%) more effective at anti-aliasing than the Radeon HD 4890 1GB, and should be capable of handling higher screen resolutions while still performing well. (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: Bandwidth is the maximum amount of information (in units of MB per second) that can be transported past the external memory interface within a second. The number is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly write to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.