Radeon R7 250X 2GB vs Radeon R9 390 8G

Intro

Compare all of that to the Radeon R9 390 8G, which comes with a GPU core clock speed of 1000 MHz, and 8192 MB of GDDR5 RAM running at 1500 MHz through a 512-bit bus. It also is comprised of 2560 Stream Processors, 160 Texture Address Units, and 64 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R7 250X 2GB		95 Watts
Radeon R9 390 8G		275 Watts
	Difference: 180 Watts (189%)

Memory Bandwidth

Theoretically speaking, the Radeon R9 390 8G should perform much faster than the Radeon R7 250X 2GB in general. (explain)

Radeon R9 390 8G		384000 MB/sec
Radeon R7 250X 2GB		72000 MB/sec
	Difference: 312000 (433%)

Texel Rate

The Radeon R9 390 8G will be much (about 300%) faster with regards to texture filtering than the Radeon R7 250X 2GB. (explain)

Radeon R9 390 8G		160000 Mtexels/sec
Radeon R7 250X 2GB		40000 Mtexels/sec
	Difference: 120000 (300%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon R9 390 8G is a better choice, by a large margin. (explain)

Radeon R9 390 8G		64000 Mpixels/sec
Radeon R7 250X 2GB		16000 Mpixels/sec
	Difference: 48000 (300%)

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 information (counted in MB per second) that can be moved past the external memory interface within a second. It's worked out by multiplying the interface width by the speed of its memory. If it uses DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster 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 applied in one second. This number is worked out by multiplying the total texture units by the core speed of the chip. The higher this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

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