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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 is set to run at 1125 MHz through a 128-bit bus. It also is made up of 640 Stream Processors, 40 TAUs, and 16 ROPs.

Compare those specs to the Radeon HD 7870, which comes with a core clock frequency of 1000 MHz and a GDDR5 memory frequency of 1200 MHz. It also features a 256-bit memory bus, and makes use of a 28 nm design. It is made up of 1280 SPUs, 80 Texture Address Units, and 32 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 7870 175 Watts
Difference: 95 Watts (119%)

Memory Bandwidth

As far as performance goes, the Radeon HD 7870 should in theory be quite a bit better than the Radeon HD 7770 overall. (explain)

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

Texel Rate

The Radeon HD 7870 should be a lot (more or less 100%) more effective at anisotropic filtering 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 quite a bit (approximately 100%) better at anti-aliasing than the Radeon HD 7770, and will be capable of handling higher screen resolutions more effectively. (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: Bandwidth is the max amount of information (measured in megabytes per second) that can be transferred across the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory clock speed. In the case of DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This number is calculated 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 in a second.

Pixel Rate: Pixel rate is the most pixels the video 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 number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential 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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