GeForce GTX 275 vs Radeon HD 4790

Intro

Compare those specs to the Radeon HD 4790, which uses a 55 nm design. AMD has set the core frequency at 600 MHz. The GDDR5 RAM is set to run at a frequency of 800 MHz on this model. It features 640(128x5) SPUs as well as 32 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the GeForce GTX 275 is 24% faster than the Radeon HD 4790 overall, because of its greater bandwidth. (explain)

GeForce GTX 275		127008 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 24608 (24%)

Texel Rate

The GeForce GTX 275 is a lot (more or less 164%) more effective at anisotropic filtering than the Radeon HD 4790. (explain)

GeForce GTX 275		50640 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 31440 (164%)

Pixel Rate

The GeForce GTX 275 will be quite a bit (more or less 85%) more effective at full screen anti-aliasing than the Radeon HD 4790, and also should be capable of handling higher screen resolutions without losing too much performance. (explain)

GeForce GTX 275		17724 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 8124 (85%)

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 largest amount of information (counted in megabytes per second) that can be transferred past the external memory interface in one second. It's worked out by multiplying the interface width by its memory speed. In the case of DDR memory, it must be multiplied by 2 again. If 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 amount of texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total number of texture units of the card 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 amount of pixels that the graphics chip could possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka 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 - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.