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Radeon HD 4870 512MB vs Radeon HD 7850

Intro

The Radeon HD 4870 512MB has a GPU core clock speed of 750 MHz, and the 512 MB of GDDR5 memory runs at 900 MHz through a 256-bit bus. It also is made up of 800(160x5) Stream Processors, 40 Texture Address Units, and 16 ROPs.

Compare all that to the Radeon HD 7850, which features core clock speeds of 860 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 memory. It features 1024 SPUs along with 64 TAUs and 32 ROPs.

(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 will be 33% faster than the Radeon HD 4870 512MB in general, due to 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 is quite a bit (about 83%) faster with regards to texture filtering 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

The Radeon HD 7850 will be much (more or less 129%) faster with regards to FSAA than the Radeon HD 4870 512MB, and also will be capable of handling higher resolutions better. (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

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

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 900 MHz (3600 MHz effective) 1200 MHz (4800 MHz effective)
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 (in units of megabytes per second) that can be moved past the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory speed. In the case of DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better 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 are processed per second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.

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