GeForce GTX 275 vs Radeon HD 4870 2GB

Intro

Compare those specs to the Radeon HD 4870 2GB, which comes with a clock frequency of 750 MHz and a GDDR5 memory speed of 900 MHz. It also makes use of a 256-bit bus, and makes use of a 55 nm design. It 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 4870 2GB		150 Watts
GeForce GTX 275		219 Watts
	Difference: 69 Watts (46%)

Memory Bandwidth

As far as performance goes, the GeForce GTX 275 should in theory be a little bit better than the Radeon HD 4870 2GB in general. (explain)

GeForce GTX 275		127008 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 11808 (10%)

Texel Rate

The GeForce GTX 275 will be quite a bit (approximately 69%) more effective at anisotropic filtering than the Radeon HD 4870 2GB. (explain)

GeForce GTX 275		50640 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 20640 (69%)

Pixel Rate

The GeForce GTX 275 will be quite a bit (more or less 48%) better at FSAA than the Radeon HD 4870 2GB, and also able to handle higher screen resolutions without losing too much performance. (explain)

GeForce GTX 275		17724 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 5724 (48%)

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 max amount of information (measured in MB per second) that can be transferred over the external memory interface in a second. The number is calculated by multiplying the interface width by its memory speed. In the case of DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better 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 are applied in one second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better 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 in one second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the card's clock speed. 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 output rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.