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Radeon HD 7770 vs Radeon HD 7870

Intro

The Radeon HD 7770 has a GPU core clock speed of 1000 MHz, and the 1024 MB of GDDR5 RAM runs at 1125 MHz through a 128-bit bus. It also is comprised of 640 SPUs, 40 TAUs, and 16 ROPs.

Compare all that to the Radeon HD 7870, which has core clock speeds of 1000 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 RAM. It features 1280 SPUs along with 80 Texture Address Units and 32 Rasterization Operator Units.

(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

The Radeon HD 7870, in theory, should perform much 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 will be a lot (more or less 100%) faster with regards to AF than the Radeon HD 7770. (explain)

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

Pixel Rate

The Radeon HD 7870 is a lot (about 100%) more effective at anti-aliasing than the Radeon HD 7770, and also will be capable of handling higher screen resolutions better. (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 maximum amount of information (measured in MB per second) that can be moved past the external memory interface in one second. It is worked out by multiplying the bus width by the speed of its memory. If the card has DDR RAM, it must 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, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output 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 get to 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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