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Radeon HD 4870 512MB vs Radeon HD 7850

Intro

The Radeon HD 4870 512MB features a GPU core speed of 750 MHz, and the 512 MB of GDDR5 RAM runs at 900 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 TAUs, and 16 Raster Operation Units.

Compare all that to the Radeon HD 7850, which uses a 28 nm design. AMD has set the core speed at 860 MHz. The GDDR5 RAM is set to run at a frequency of 1200 MHz on this specific model. It features 1024 SPUs along with 64 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7850 130 Watts
Radeon HD 4870 512MB 150 Watts
Difference: 20 Watts (15%)

Memory Bandwidth

In theory, the Radeon HD 7850 should be 33% faster than the Radeon HD 4870 512MB overall, because of its higher bandwidth. (explain)

Radeon HD 7850 153600 MB/sec
Radeon HD 4870 512MB 115200 MB/sec
Difference: 38400 (33%)

Texel Rate

The Radeon HD 7850 will be a lot (more or less 83%) more effective at AF than the Radeon HD 4870 512MB. (explain)

Radeon HD 7850 55040 Mtexels/sec
Radeon HD 4870 512MB 30000 Mtexels/sec
Difference: 25040 (83%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7850 is superior to the Radeon HD 4870 512MB, by far. (explain)

Radeon HD 7850 27520 Mpixels/sec
Radeon HD 4870 512MB 12000 Mpixels/sec
Difference: 15520 (129%)

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

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Radeon HD 4870 512MB

Amazon.com

Radeon HD 7850

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

Display Specifications

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Model Radeon HD 4870 512MB Radeon HD 7850
Manufacturer AMD AMD
Year Jun 25, 2008 March 2012
Code Name RV770 XT Pitcairn Pro
Fab Process 55 nm 28 nm
Bus PCIe 2.0 x16 PCIe 3.0 x16
Memory 512 MB 2048 MB
Core Speed 750 MHz 860 MHz
Shader Speed N/A MHz (N/A) MHz
Memory Speed 3600 MHz 4800 MHz
Unified Shaders 800(160x5) 1024
Texture Mapping Units 40 64
Render Output Units 16 32
Bus Type GDDR5 GDDR5
Bus Width 256-bit 256-bit
DirectX Version DirectX 10.1 DirectX 11.1
OpenGL Version OpenGL 3.0 OpenGL 4.2
Power (Max TDP) 150 watts 130 watts
Shader Model 4.1 5.0
Bandwidth 115200 MB/sec 153600 MB/sec
Texel Rate 30000 Mtexels/sec 55040 Mtexels/sec
Pixel Rate 12000 Mpixels/sec 27520 Mpixels/sec

Memory Bandwidth: Bandwidth is the max amount of information (measured in megabytes per second) that can be transported across the external memory interface in a second. It's calculated by multiplying the card's bus width by its memory speed. If it uses DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. 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 number of texture map elements (texels) that are applied in one 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 video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.

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