GeForce GTX 660 vs Radeon HD 6990

Intro

Compare all that to the Radeon HD 6990, which has core clock speeds of 830 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 RAM. It features 1536 SPUs along with 96 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Benchmarks

These are real-world performance benchmarks that were submitted by Hardware Compare users. The scores seen here are the average of all benchmarks submitted for each respective test and hardware.

3DMark Fire Strike Graphics Score

Radeon HD 6990		5820 points
GeForce GTX 660		5063 points
	Difference: 757 (15%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 660		140 Watts
Radeon HD 6990		375 Watts
	Difference: 235 Watts (168%)

Memory Bandwidth

Theoretically, the Radeon HD 6990 should perform much faster than the GeForce GTX 660 overall. (explain)

Radeon HD 6990		320000 MB/sec
GeForce GTX 660		144192 MB/sec
	Difference: 175808 (122%)

Texel Rate

The Radeon HD 6990 should be a lot (more or less 103%) more effective at anisotropic filtering than the GeForce GTX 660. (explain)

Radeon HD 6990		159360 Mtexels/sec
GeForce GTX 660		78400 Mtexels/sec
	Difference: 80960 (103%)

Pixel Rate

The Radeon HD 6990 is quite a bit (more or less 126%) more effective at AA than the GeForce GTX 660, and should be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 6990		53120 Mpixels/sec
GeForce GTX 660		23520 Mpixels/sec
	Difference: 29600 (126%)

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 maximum amount of information (in units of MB per second) that can be transferred over the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at 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 can possibly record to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.