GeForce GTX 275 vs Radeon HD 4870 X2

Intro

Compare those specs to the Radeon HD 4870 X2, which has a clock speed of 750 MHz and a GDDR5 memory frequency of 900 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 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 275		219 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 131 Watts (60%)

Memory Bandwidth

In theory, the Radeon HD 4870 X2 will be 81% faster than the GeForce GTX 275 overall, because of its greater data rate. (explain)

Radeon HD 4870 X2		230400 MB/sec
GeForce GTX 275		127008 MB/sec
	Difference: 103392 (81%)

Texel Rate

The Radeon HD 4870 X2 will be a bit (approximately 18%) more effective at anisotropic filtering than the GeForce GTX 275. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
GeForce GTX 275		50640 Mtexels/sec
	Difference: 9360 (18%)

Pixel Rate

The Radeon HD 4870 X2 is much (about 35%) faster with regards to FSAA than the GeForce GTX 275, and able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
GeForce GTX 275		17724 Mpixels/sec
	Difference: 6276 (35%)

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 largest amount of data (in units of MB per second) that can be transported across the external memory interface within a second. It is worked out by multiplying the card's interface width by its memory speed. If the card has DDR 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, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This number is calculated by multiplying the total amount of texture units by the core speed of the chip. The better this number, 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 maximum number of pixels that the graphics chip could possibly write to the 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 - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.