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Radeon HD 4790 vs Radeon HD 4870 2GB
Intro
The Radeon HD 4790 features a clock frequency of 600 MHz and a GDDR5 memory speed of 800 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It is comprised of 640(128x5) SPUs, 32 TAUs, and 16 Raster Operation Units.Compare those specs to the Radeon HD 4870 2GB, which comes with GPU clock speed of 750 MHz, and 2048 MB of GDDR5 memory set to run at 900 MHz through a 256-bit bus. It also features 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.
Power Usage and Theoretical Benchmarks
Memory Bandwidth
The Radeon HD 4870 2GB, in theory, should perform a little bit faster than the Radeon HD 4790 in general. (explain)
| Radeon HD 4870 2GB |
|
115200 MB/sec |
| Radeon HD 4790 |
|
102400 MB/sec |
|
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Texel Rate
The Radeon HD 4870 2GB will be much (approximately 56%) better at anisotropic filtering than the Radeon HD 4790. (explain)| Radeon HD 4870 2GB |
|
30000 Mtexels/sec |
| Radeon HD 4790 |
|
19200 Mtexels/sec |
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Pixel Rate
The Radeon HD 4870 2GB is quite a bit (about 25%) more effective at FSAA than the Radeon HD 4790, and will be able to handle higher resolutions more effectively. (explain)| Radeon HD 4870 2GB |
|
12000 Mpixels/sec |
| Radeon HD 4790 |
|
9600 Mpixels/sec |
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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 4790Amazon.com
Other US-based stores
Amazon.co.uk
Amazon.de
Amazon.fr
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Radeon HD 4870 2GBAmazon.com
Other US-based stores
Amazon.co.uk
Amazon.de
Amazon.fr
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Specifications
| Model | Radeon HD 4790 | Radeon HD 4870 2GB |
|---|---|---|
| Manufacturer | ATi | ATi |
| Year | 2009 | Jun 25, 2008 |
| Code Name | RV790 | RV770 XT |
| Fab Process | 55 nm | 55 nm |
| Bus | PCIe 2.0 x16 | PCIe 2.0 x16 |
| Memory | 512 MB | 2048 MB |
| Core Speed | 600 MHz | 750 MHz |
| Shader Speed | N/A MHz | (N/A) MHz |
| Memory Speed | 800 MHz | 900 MHz |
| Unified Shaders | 640(128x5) | 800(160x5) |
| Texture Mapping Units | 32 | 40 |
| Render Output Units | 16 | 16 |
| Bus Type | GDDR5 | GDDR5 |
| Bus Width | 256-bit | 256-bit |
| DirectX Version | DirectX 10.1 | DirectX 10.1 |
| OpenGL Version | OpenGL 3.0 | OpenGL 3.0 |
| Power (Max TDP) | N/A watts | 150 watts |
| Shader Model | 4.1 | 4.1 |
| Bandwidth | 102400 MB/sec | 115200 MB/sec |
| Texel Rate | 19200 Mtexels/sec | 30000 Mtexels/sec |
| Pixel Rate | 9600 Mpixels/sec | 12000 Mpixels/sec |
Memory Bandwidth: Memory bandwidth is the max amount of information (in units of MB per second) that can be moved across the external memory interface in a second. It's worked out by multiplying the interface width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better 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 in one second. This figure is worked out by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the graphics 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 the video card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the clock 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 quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.
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