GeForce GT 640 DDR3 vs Radeon HD 7990

Intro

Compare those specs to the Radeon HD 7990, which uses a 28 nm design. AMD has clocked the core speed at 950 MHz. The GDDR5 RAM is set to run at a speed of 1500 MHz on this particular model. It features 2048 SPUs as well as 128 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Benchmarks

These are real-world performance benchmarks that were submitted by Hardware Compare users. The scores seen here are the average of all benchmarks submitted for each respective test and hardware.

3DMark Fire Strike Graphics Score

Radeon HD 7990		15520 points
GeForce GT 640 DDR3		1560 points
	Difference: 13960 (895%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 7990		375 Watts
	Difference: 310 Watts (477%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7990 will be 910% quicker than the GeForce GT 640 DDR3 overall, due to its higher data rate. (explain)

Radeon HD 7990		576000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 518976 (910%)

Texel Rate

The Radeon HD 7990 will be much (about 744%) more effective at anisotropic filtering than the GeForce GT 640 DDR3. (explain)

Radeon HD 7990		243200 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 214400 (744%)

Pixel Rate

The Radeon HD 7990 will be a lot (approximately 322%) more effective at FSAA than the GeForce GT 640 DDR3, and capable of handling higher resolutions while still performing well. (explain)

Radeon HD 7990		60800 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 46400 (322%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of information (measured in megabytes per second) that can be transferred across the external memory interface in one second. The number is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR type RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.