GeForce GTX 660 vs Radeon HD 6990

Intro

Compare all of that to the Radeon HD 6990, which features GPU clock speed of 830 MHz, and 2048 MB of GDDR5 RAM running at 1250 MHz through a 256-bit bus. It also is made up of 1536 SPUs, 96 Texture Address Units, and 32 ROPs.

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

As far as performance goes, the Radeon HD 6990 should in theory be a lot better 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 (about 103%) better at texture 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 a lot (approximately 126%) faster with regards to AA than the GeForce GTX 660, and will be capable of handling higher 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: Bandwidth is the max amount of data (measured in MB per second) that can be transferred over the external memory interface in one second. The number is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This is calculated by multiplying the total 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 applied in one second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to the local memory in a second - measured in millions of pixels per second. The figure 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 fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.