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Radeon HD 7770 vs Radeon HD 7870

Intro

The Radeon HD 7770 features core clock speeds of 1000 MHz on the GPU, and 1125 MHz on the 1024 MB of GDDR5 RAM. It features 640 SPUs as well as 40 Texture Address Units and 16 ROPs.

Compare that to the Radeon HD 7870, which comes with a GPU core clock speed of 1000 MHz, and 2048 MB of GDDR5 memory running at 1200 MHz through a 256-bit bus. It also features 1280 SPUs, 80 TAUs, and 32 ROPs.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770 80 Watts
Radeon HD 7870 175 Watts
Difference: 95 Watts (119%)

Memory Bandwidth

In theory, the Radeon HD 7870 should be a lot faster than the Radeon HD 7770 in general. (explain)

Radeon HD 7870 153600 MB/sec
Radeon HD 7770 72000 MB/sec
Difference: 81600 (113%)

Texel Rate

The Radeon HD 7870 should be much (approximately 100%) faster with regards to texture filtering than the Radeon HD 7770. (explain)

Radeon HD 7870 80000 Mtexels/sec
Radeon HD 7770 40000 Mtexels/sec
Difference: 40000 (100%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7870 is a better choice, and very much so. (explain)

Radeon HD 7870 32000 Mpixels/sec
Radeon HD 7770 16000 Mpixels/sec
Difference: 16000 (100%)

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 7770

Amazon.com

Radeon HD 7870

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 7770 Radeon HD 7870
Manufacturer AMD AMD
Year February 2012 March 2012
Code Name Cape Verde XT Pitcairn XT
Fab Process 28 nm 28 nm
Bus PCIe 3.0 x16 PCIe 3.0 x16
Memory 1024 MB 2048 MB
Core Speed 1000 MHz 1000 MHz
Shader Speed N/A MHz (N/A) MHz
Memory Speed 1125 MHz (4500 MHz effective) 1200 MHz (4800 MHz effective)
Unified Shaders 640 1280
Texture Mapping Units 40 80
Render Output Units 16 32
Bus Type GDDR5 GDDR5
Bus Width 128-bit 256-bit
DirectX Version DirectX 11.1 DirectX 11.1
OpenGL Version OpenGL 4.2 OpenGL 4.2
Power (Max TDP) 80 watts 175 watts
Shader Model 5.0 5.0
Bandwidth 72000 MB/sec 153600 MB/sec
Texel Rate 40000 Mtexels/sec 80000 Mtexels/sec
Pixel Rate 16000 Mpixels/sec 32000 Mpixels/sec

Memory Bandwidth: Memory bandwidth is the largest amount of information (measured in MB per second) that can be moved across the external memory interface within a second. The number 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 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high 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 clock speed of the chip. The higher this number, the better the 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 amount of pixels the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.

Comments

One Response to “Radeon HD 7770 vs Radeon HD 7870”
FB Appo says:
When comparing the Radeon 7870 to the 7770, there is comparisson the 7870 is way better and the 7770 is not worth investing in.

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