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GeForce 9800 GT 1GB vs GeForce GT 640 DDR3
Intro
The GeForce 9800 GT 1GB features a GPU clock speed of 600 MHz, and the 1024 MB of GDDR3 RAM is set to run at 900 MHz through a 256-bit bus. It also features 112 SPUs, 56 TAUs, and 16 ROPs.Compare those specs to the GeForce GT 640 DDR3, which has GPU clock speed of 900 MHz, and 2048 MB of DDR3 RAM set to run at 1782 MHz through a 128-bit bus. It also is made up of 384 SPUs, 32 Texture Address Units, and 16 ROPs.
Power Usage and Theoretical Benchmarks
Power Consumption (Max TDP)
| GeForce GT 640 DDR3 |
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65 Watts |
| GeForce 9800 GT 1GB |
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105 Watts |
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Memory Bandwidth
Performance-wise, the GeForce 9800 GT 1GB should theoretically be just a bit superior to the GeForce GT 640 DDR3 overall. (explain)
| GeForce 9800 GT 1GB |
|
57600 MB/sec |
| GeForce GT 640 DDR3 |
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57024 MB/sec |
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Texel Rate
The GeForce 9800 GT 1GB will be a bit (approximately 17%) better at anisotropic filtering than the GeForce GT 640 DDR3. (explain)| GeForce 9800 GT 1GB |
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33600 Mtexels/sec |
| GeForce GT 640 DDR3 |
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28800 Mtexels/sec |
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Pixel Rate
The GeForce GT 640 DDR3 will be a lot (more or less 50%) more effective at AA than the GeForce 9800 GT 1GB, and also should be capable of handling higher resolutions without losing too much performance. (explain)| GeForce GT 640 DDR3 |
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14400 Mpixels/sec |
| GeForce 9800 GT 1GB |
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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.
GeForce 9800 GT 1GBAmazon.com
Other US-based stores
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GeForce GT 640 DDR3Amazon.com
Other US-based stores
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Specifications
| Model | GeForce 9800 GT 1GB | GeForce GT 640 DDR3 |
|---|---|---|
| Manufacturer | nVidia | nVidia |
| Year | July 2008 | June 2012 |
| Code Name | G92a/b | GK107 |
| Fab Process | 65/55 nm | 28 nm |
| Bus | PCIe x16 2.0 | PCIe 3.0 x16 |
| Memory | 1024 MB | 2048 MB |
| Core Speed | 600 MHz | 900 MHz |
| Shader Speed | 1500 MHz | 900 MHz |
| Memory Speed | 900 MHz (1800 MHz effective) | 1782 MHz (3564 MHz effective) |
| Unified Shaders | 112 | 384 |
| Texture Mapping Units | 56 | 32 |
| Render Output Units | 16 | 16 |
| Bus Type | GDDR3 | DDR3 |
| Bus Width | 256-bit | 128-bit |
| DirectX Version | DirectX 10 | DirectX 11.1 |
| OpenGL Version | OpenGL 3.0 | OpenGL 4.2 |
| Power (Max TDP) | 105 watts | 65 watts |
| Shader Model | 4.0 | 5.0 |
| Bandwidth | 57600 MB/sec | 57024 MB/sec |
| Texel Rate | 33600 Mtexels/sec | 28800 Mtexels/sec |
| Pixel Rate | 9600 Mpixels/sec | 14400 Mpixels/sec |
Memory Bandwidth: Bandwidth is the max amount of information (in units of megabytes per second) that can be moved across the external memory interface in one second. It is worked out by multiplying the interface width by the speed of its memory. If it uses DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.
Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This figure is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.
Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.
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