GeForce 9400 GT 256MB vs Geforce GTX 780

Intro

Compare those specs to the Geforce GTX 780, which comes with core speeds of 863 MHz on the GPU, and 1502 MHz on the 3072 MB of GDDR5 RAM. It features 2304 SPUs as well as 192 Texture Address Units and 48 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 9400 GT 256MB		50 Watts
Geforce GTX 780		250 Watts
	Difference: 200 Watts (400%)

Memory Bandwidth

As far as performance goes, the Geforce GTX 780 should in theory be a lot better than the GeForce 9400 GT 256MB overall. (explain)

Geforce GTX 780		288384 MB/sec
GeForce 9400 GT 256MB		12800 MB/sec
	Difference: 275584 (2153%)

Texel Rate

The Geforce GTX 780 should be quite a bit (approximately 3666%) better at AF than the GeForce 9400 GT 256MB. (explain)

Geforce GTX 780		165696 Mtexels/sec
GeForce 9400 GT 256MB		4400 Mtexels/sec
	Difference: 161296 (3666%)

Pixel Rate

The Geforce GTX 780 will be a lot (approximately 1783%) better at anti-aliasing than the GeForce 9400 GT 256MB, and capable of handling higher screen resolutions without slowing down too much. (explain)

Geforce GTX 780		41424 Mpixels/sec
GeForce 9400 GT 256MB		2200 Mpixels/sec
	Difference: 39224 (1783%)

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 (counted in MB per second) that can be moved over the external memory interface in one second. It's calculated by multiplying the bus width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could 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 ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.