GeForce GT 640 DDR3 vs Radeon HD 7790

Intro

Compare that to the Radeon HD 7790, which comes with a clock frequency of 1000 MHz and a GDDR5 memory frequency of 1500 MHz. It also makes use of a 128-bit memory bus, and makes use of a 28 nm design. It is comprised of 896 SPUs, 56 TAUs, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

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 7790		4330 points
GeForce GT 640 DDR3		1560 points
	Difference: 2770 (178%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 7790		85 Watts
	Difference: 20 Watts (31%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7790 will be 68% faster than the GeForce GT 640 DDR3 overall, because of its higher data rate. (explain)

Radeon HD 7790		96000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 38976 (68%)

Texel Rate

The Radeon HD 7790 is a lot (approximately 94%) better at texture filtering than the GeForce GT 640 DDR3. (explain)

Radeon HD 7790		56000 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 27200 (94%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 7790 is superior to the GeForce GT 640 DDR3, though not by far. (explain)

Radeon HD 7790		16000 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 1600 (11%)

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

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of information (measured in megabytes per second) that can be transferred across the external memory interface in one second. It is worked out by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.