GeForce GTX 275 vs Radeon HD 4790

Intro

Compare that to the Radeon HD 4790, which makes use of a 55 nm design. ATi has set the core frequency at 600 MHz. The GDDR5 memory runs at a frequency of 800 MHz on this model. It features 640(128x5) SPUs as well as 32 Texture Address Units and 16 ROPs.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Memory Bandwidth

As far as performance goes, the GeForce GTX 275 should theoretically be much better than the Radeon HD 4790 overall. (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 should be quite a bit (approximately 85%) better at anti-aliasing than the Radeon HD 4790, and able to handle higher screen resolutions more effectively. (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 data (in units of megabytes per second) that can be transferred across the external memory interface in one second. It's calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This number is calculated by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, 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 amount of pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.