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Radeon HD 6770 vs Radeon HD 7770

Intro

The Radeon HD 6770 makes use of a 40 nm design. AMD has set the core speed at 900 MHz. The GDDR5 RAM runs at a frequency of 1050 MHz on this model. It features 800 SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Compare that to the Radeon HD 7770, which comes with a core clock speed of 1000 MHz and a GDDR5 memory speed of 1125 MHz. It also uses a 128-bit bus, and uses a 28 nm design. It is comprised of 640 SPUs, 40 TAUs, and 16 Raster Operation Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770 80 Watts
Radeon HD 6770 108 Watts
Difference: 28 Watts (35%)

Memory Bandwidth

As far as performance goes, the Radeon HD 7770 should in theory be a bit better than the Radeon HD 6770 in general. (explain)

Radeon HD 7770 72000 MB/sec
Radeon HD 6770 67200 MB/sec
Difference: 4800 (7%)

Texel Rate

The Radeon HD 7770 will be a little bit (approximately 11%) faster with regards to AF than the Radeon HD 6770. (explain)

Radeon HD 7770 40000 Mtexels/sec
Radeon HD 6770 36000 Mtexels/sec
Difference: 4000 (11%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 7770 is a better choice, but it probably won't make a huge difference. (explain)

Radeon HD 7770 16000 Mpixels/sec
Radeon HD 6770 14400 Mpixels/sec
Difference: 1600 (11%)

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

Radeon HD 6770

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 Radeon HD 6770 Radeon HD 7770
Manufacturer AMD AMD
Year January 2011 February 2012
Code Name Juniper XT Cape Verde XT
Fab Process 40 nm 28 nm
Bus PCIe x16 PCIe 3.0 x16
Memory 512 MB 1024 MB
Core Speed 900 MHz 1000 MHz
Shader Speed N/A MHz (N/A) MHz
Memory Speed 1050 MHz (4200 MHz effective) 1125 MHz (4500 MHz effective)
Unified Shaders 800 640
Texture Mapping Units 40 40
Render Output Units 16 16
Bus Type GDDR5 GDDR5
Bus Width 128-bit 128-bit
DirectX Version DirectX 11 DirectX 11.1
OpenGL Version OpenGL 4.1 OpenGL 4.2
Power (Max TDP) 108 watts 80 watts
Shader Model 5.0 5.0
Bandwidth 67200 MB/sec 72000 MB/sec
Texel Rate 36000 Mtexels/sec 40000 Mtexels/sec
Pixel Rate 14400 Mpixels/sec 16000 Mpixels/sec

Memory Bandwidth: Bandwidth is the max amount of data (measured in MB per second) that can be transported past the external memory interface in a second. It is worked out by multiplying the card's interface width by the speed of its memory. In the case of DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, 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 figure is worked out by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output 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 potential to get to the max fill rate.

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