GeForce GTX 660 vs Radeon HD 4890 1GB

Intro

Compare that to the Radeon HD 4890 1GB, which features a clock frequency of 1000 MHz and a GDDR5 memory speed of 975 MHz. It also makes use of a 256-bit memory bus, and uses a 55 nm design. It is made up of 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 660		140 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 50 Watts (36%)

Memory Bandwidth

The GeForce GTX 660 should theoretically be just a bit faster than the Radeon HD 4890 1GB in general. (explain)

GeForce GTX 660		144192 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 19392 (16%)

Texel Rate

The GeForce GTX 660 will be much (more or less 96%) faster with regards to texture filtering than the Radeon HD 4890 1GB. (explain)

GeForce GTX 660		78400 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 38400 (96%)

Pixel Rate

If running with a high resolution is important to you, then the GeForce GTX 660 is superior to the Radeon HD 4890 1GB, and very much so. (explain)

GeForce GTX 660		23520 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 7520 (47%)

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 largest amount of information (measured in MB per second) that can be moved over the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. In the case of DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed per second. This is worked out by multiplying the total amount of texture units 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 in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.