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Radeon HD 4870 512MB vs Radeon HD 7850

Intro

The Radeon HD 4870 512MB features a core clock frequency of 750 MHz and a GDDR5 memory frequency of 900 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Compare those specs 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

As far as performance goes, the Radeon HD 7850 should in theory be a lot superior to the Radeon HD 4870 512MB in general. (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 anisotropic 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

If running with high levels of AA is important to you, then the Radeon HD 7850 is superior to the Radeon HD 4870 512MB, and very much so. (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

Please note that the price comparisons are based on search keywords, and might not be the exact same card listed on this page. We have no control over the accuracy of their search results.

Radeon HD 4870 512MB

Amazon.com

Other US-based stores

Radeon HD 7850

Amazon.com

Other US-based stores

Specifications

Model Radeon HD 4870 512MB Radeon HD 7850
Manufacturer ATi ATi
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: Memory bandwidth is the largest amount of data (in units of MB per second) that can be transported past the external memory interface in a second. It's worked out by multiplying the bus width by its memory speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's 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 texture map elements (texels) that can be processed per second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.

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