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GeForce GTX 660 vs Radeon HD 7770

Intro

The GeForce GTX 660 comes with clock speeds of 980 MHz on the GPU, and 1502 MHz on the 2048 MB of GDDR5 memory. It features 960 SPUs as well as 80 TAUs and 24 Rasterization Operator Units.

Compare those specs to the Radeon HD 7770, which uses a 28 nm design. AMD has set the core speed at 1000 MHz. The GDDR5 RAM runs at a frequency of 1125 MHz on this card. It features 640 SPUs as well as 40 TAUs and 16 Rasterization Operator Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770 80 Watts
GeForce GTX 660 140 Watts
Difference: 60 Watts (75%)

Memory Bandwidth

As far as performance goes, the GeForce GTX 660 should in theory be quite a bit superior to the Radeon HD 7770 in general. (explain)

GeForce GTX 660 144192 MB/sec
Radeon HD 7770 72000 MB/sec
Difference: 72192 (100%)

Texel Rate

The GeForce GTX 660 is a lot (approximately 96%) faster with regards to texture filtering than the Radeon HD 7770. (explain)

GeForce GTX 660 78400 Mtexels/sec
Radeon HD 7770 40000 Mtexels/sec
Difference: 38400 (96%)

Pixel Rate

The GeForce GTX 660 is quite a bit (about 47%) faster with regards to anti-aliasing than the Radeon HD 7770, and capable of handling higher resolutions better. (explain)

GeForce GTX 660 23520 Mpixels/sec
Radeon HD 7770 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

GeForce GTX 660

Amazon.com

Radeon HD 7770

Amazon.com

Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.

Specifications

Model GeForce GTX 660 Radeon HD 7770
Manufacturer nVidia AMD
Year September 2012 February 2012
Code Name GK106 Cape Verde XT
Fab Process 28 nm 28 nm
Bus PCIe 3.0 x16 PCIe 3.0 x16
Memory 2048 MB 1024 MB
Core Speed 980 MHz 1000 MHz
Shader Speed 980 MHz (N/A) MHz
Memory Speed 1502 MHz (6008 MHz effective) 1125 MHz (4500 MHz effective)
Unified Shaders 960 640
Texture Mapping Units 80 40
Render Output Units 24 16
Bus Type GDDR5 GDDR5
Bus Width 192-bit 128-bit
DirectX Version DirectX 11.0 DirectX 11.1
OpenGL Version OpenGL 4.3 OpenGL 4.2
Power (Max TDP) 140 watts 80 watts
Shader Model 5.0 5.0
Bandwidth 144192 MB/sec 72000 MB/sec
Texel Rate 78400 Mtexels/sec 40000 Mtexels/sec
Pixel Rate 23520 Mpixels/sec 16000 Mpixels/sec

Memory Bandwidth: Bandwidth is the max amount of data (in units of MB per second) that can be transported across the external memory interface within a second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total texture units by the core speed of the chip. The higher this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.

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