Radeon HD 7870 XT vs Radeon R9 M395X

Intro

Compare those specifications to the Radeon R9 M395X, which has GPU core speed of 723 MHz, and 4096 MB of GDDR5 memory set to run at 1250 MHz through a 256-bit bus. It also is made up of 2048 Stream Processors, 128 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M395X		125 Watts
Radeon HD 7870 XT		185 Watts
	Difference: 60 Watts (48%)

Memory Bandwidth

In theory, the Radeon HD 7870 XT will be 20% faster than the Radeon R9 M395X in general, due to its higher data rate. (explain)

Radeon HD 7870 XT		192000 MB/sec
Radeon R9 M395X		160000 MB/sec
	Difference: 32000 (20%)

Texel Rate

The Radeon R9 M395X will be a bit (about 4%) faster with regards to texture filtering than the Radeon HD 7870 XT. (explain)

Radeon R9 M395X		92544 Mtexels/sec
Radeon HD 7870 XT		88800 Mtexels/sec
	Difference: 3744 (4%)

Pixel Rate

The Radeon HD 7870 XT will be a lot (approximately 28%) faster with regards to FSAA than the Radeon R9 M395X, and capable of handling higher resolutions better. (explain)

Radeon HD 7870 XT		29600 Mpixels/sec
Radeon R9 M395X		23136 Mpixels/sec
	Difference: 6464 (28%)

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 (in units of megabytes per second) that can be transported over the external memory interface in a second. The number is worked out by multiplying the card's bus width by its memory speed. If the card has DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The better 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 a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip 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 amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.