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GeForce GT 640 DDR3 vs GeForce GTX 650

Intro

The GeForce GT 640 DDR3 features clock speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs along with 32 Texture Address Units and 16 ROPs.

Compare those specifications to the GeForce GTX 650, which features GPU clock speed of 1058 MHz, and 2048 MB of GDDR5 RAM running at 1250 MHz through a 128-bit bus. It also is comprised of 384 Stream Processors, 32 Texture Address Units, and 16 Raster Operation Units.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GTX 650 64 Watts
GeForce GT 640 DDR3 65 Watts
Difference: 1 Watts (2%)

Memory Bandwidth

In theory, the GeForce GTX 650 should be much faster than the GeForce GT 640 DDR3 in general. (explain)

GeForce GTX 650 80000 MB/sec
GeForce GT 640 DDR3 57024 MB/sec
Difference: 22976 (40%)

Texel Rate

The GeForce GTX 650 is a little bit (more or less 18%) faster with regards to AF than the GeForce GT 640 DDR3. (explain)

GeForce GTX 650 33856 Mtexels/sec
GeForce GT 640 DDR3 28800 Mtexels/sec
Difference: 5056 (18%)

Pixel Rate

The GeForce GTX 650 is just a bit (approximately 18%) more effective at FSAA than the GeForce GT 640 DDR3, and also will be capable of handling higher screen resolutions without losing too much performance. (explain)

GeForce GTX 650 16928 Mpixels/sec
GeForce GT 640 DDR3 14400 Mpixels/sec
Difference: 2528 (18%)

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 GT 640 DDR3

Amazon.com

Other US-based stores

GeForce GTX 650

Amazon.com

Other US-based stores

Specifications

Model GeForce GT 640 DDR3 GeForce GTX 650
Manufacturer nVidia nVidia
Year June 2012 September 2012
Code Name GK107 GK107
Fab Process 28 nm 28 nm
Bus PCIe 3.0 x16 PCIe 3.0 x16
Memory 2048 MB 2048 MB
Core Speed 900 MHz 1058 MHz
Shader Speed 900 MHz 1058 MHz
Memory Speed 1782 MHz (3564 MHz effective) 1250 MHz (5000 MHz effective)
Unified Shaders 384 384
Texture Mapping Units 32 32
Render Output Units 16 16
Bus Type DDR3 GDDR5
Bus Width 128-bit 128-bit
DirectX Version DirectX 11.1 DirectX 11.1
OpenGL Version OpenGL 4.2 OpenGL 4.3
Power (Max TDP) 65 watts 64 watts
Shader Model 5.0 5.0
Bandwidth 57024 MB/sec 80000 MB/sec
Texel Rate 28800 Mtexels/sec 33856 Mtexels/sec
Pixel Rate 14400 Mpixels/sec 16928 Mpixels/sec

Memory Bandwidth: Memory bandwidth is the largest amount of information (measured in megabytes per second) that can be transported past the external memory interface in one second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better 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 number of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the 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 graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.

Comments

2 Responses to “GeForce GT 640 DDR3 vs GeForce GTX 650”
RTh says:
woow... look @ the TDP
Johnny says:
Certainly going for the GTX 650 is a better choice if you are choosing between these two cards. Why to chhoose:
The higher bandwidth & GDDR5 bus (over the outdated DDR3 bus)
And even the Power consuption is lower in the GTX 650 with much better performance.
I have both cards.

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