GeForce GTX 660 Ti vs Radeon R9 M390X

Intro

Compare those specifications to the Radeon R9 M390X, which has core speeds of 723 MHz on the GPU, and 1250 MHz on the 4096 MB of GDDR5 memory. It features 2048 SPUs along with 128 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M390X		125 Watts
GeForce GTX 660 Ti		150 Watts
	Difference: 25 Watts (20%)

Memory Bandwidth

Theoretically speaking, the Radeon R9 M390X should be 11% quicker than the GeForce GTX 660 Ti overall, because of its higher bandwidth. (explain)

Radeon R9 M390X		160000 MB/sec
GeForce GTX 660 Ti		144000 MB/sec
	Difference: 16000 (11%)

Texel Rate

The GeForce GTX 660 Ti should be just a bit (more or less 11%) faster with regards to AF than the Radeon R9 M390X. (explain)

GeForce GTX 660 Ti		102480 Mtexels/sec
Radeon R9 M390X		92544 Mtexels/sec
	Difference: 9936 (11%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon R9 M390X is a better choice, though not by far. (explain)

Radeon R9 M390X		23136 Mpixels/sec
GeForce GTX 660 Ti		21960 Mpixels/sec
	Difference: 1176 (5%)

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 MB per second) that can be transported past the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed per second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The better 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 amount of pixels that 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 amount of Render Output Units by the the core 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 output rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.