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GeForce 9800 GT 1GB vs GeForce GT 640 DDR3

Intro

The GeForce 9800 GT 1GB features a clock frequency of 600 MHz and a GDDR3 memory speed of 900 MHz. It also features a 256-bit bus, and uses a 65/55 nm design. It is comprised of 112 SPUs, 56 Texture Address Units, and 16 Raster Operation Units.

Compare those specs to the GeForce GT 640 DDR3, which makes use of a 28 nm design. nVidia has set the core speed at 900 MHz. The DDR3 RAM is set to run at a speed of 1782 MHz on this specific model. It features 384 SPUs as well as 32 TAUs and 16 Rasterization Operator Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3 65 Watts
GeForce 9800 GT 1GB 105 Watts
Difference: 40 Watts (62%)

Memory Bandwidth

As far as performance goes, the GeForce 9800 GT 1GB should in theory be just a bit better than the GeForce GT 640 DDR3 in general. (explain)

GeForce 9800 GT 1GB 57600 MB/sec
GeForce GT 640 DDR3 57024 MB/sec
Difference: 576 (1%)

Texel Rate

The GeForce 9800 GT 1GB is a bit (about 17%) faster with regards to texture filtering than the GeForce GT 640 DDR3. (explain)

GeForce 9800 GT 1GB 33600 Mtexels/sec
GeForce GT 640 DDR3 28800 Mtexels/sec
Difference: 4800 (17%)

Pixel Rate

The GeForce GT 640 DDR3 will be a lot (more or less 50%) faster with regards to anti-aliasing than the GeForce 9800 GT 1GB, and able to handle higher resolutions better. (explain)

GeForce GT 640 DDR3 14400 Mpixels/sec
GeForce 9800 GT 1GB 9600 Mpixels/sec
Difference: 4800 (50%)

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 1GB

Amazon.com

Other US-based stores

GeForce GT 640 DDR3

Amazon.com

Other US-based stores

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 data (counted in megabytes per second) that can be transferred over the external memory interface within a second. The number is calculated by multiplying the card's interface width by its memory speed. If it uses DDR type RAM, the result should 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 anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total number of texture units 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 applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.

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