GeForce GTX 660 Ti vs Radeon R9 M390X

Intro

Compare all that to the Radeon R9 M390X, which has a GPU core clock speed of 723 MHz, and 4096 MB of GDDR5 memory running at 1250 MHz through a 256-bit bus. It also features 2048 SPUs, 128 TAUs, 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 660 Ti		150 Watts
	Difference: 25 Watts (20%)

Memory Bandwidth

Performance-wise, the Radeon R9 M390X should theoretically be a bit superior to the GeForce GTX 660 Ti in general. (explain)

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

Texel Rate

The GeForce GTX 660 Ti is a little bit (more or less 11%) better at 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

The Radeon R9 M390X is a bit (about 5%) faster with regards to AA than the GeForce GTX 660 Ti, and also should be capable of handling higher resolutions without slowing down too much. (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: Bandwidth is the maximum amount of data (in units of megabytes per second) that can be transferred over the external memory interface in a second. It is calculated by multiplying the interface width by the speed of its memory. If it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, 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 texture map elements (texels) that can be processed in one second. This number is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.