Geforce GTX 680 vs Radeon R9 M390X

Intro

Compare all that to the Radeon R9 M390X, which features GPU clock speed of 723 MHz, and 4096 MB of GDDR5 memory set to run at 1250 MHz through a 256-bit bus. It also features 2048 SPUs, 128 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M390X		125 Watts
Geforce GTX 680		195 Watts
	Difference: 70 Watts (56%)

Memory Bandwidth

Theoretically speaking, the Geforce GTX 680 will be 20% faster than the Radeon R9 M390X overall, because of its greater data rate. (explain)

Geforce GTX 680		192256 MB/sec
Radeon R9 M390X		160000 MB/sec
	Difference: 32256 (20%)

Texel Rate

The Geforce GTX 680 should be quite a bit (more or less 39%) more effective at AF than the Radeon R9 M390X. (explain)

Geforce GTX 680		128768 Mtexels/sec
Radeon R9 M390X		92544 Mtexels/sec
	Difference: 36224 (39%)

Pixel Rate

If running with a high screen resolution is important to you, then the Geforce GTX 680 is the winner, by far. (explain)

Geforce GTX 680		32192 Mpixels/sec
Radeon R9 M390X		23136 Mpixels/sec
	Difference: 9056 (39%)

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 data (measured in megabytes per second) that can be moved past the external memory interface in a second. The number is worked out by multiplying the bus width by its memory clock speed. If the card has DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, 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 number of texture map elements (texels) that can be processed per second. This is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.