Radeon HD 7870 XT vs Radeon R9 M390X

Intro

Compare those specs to the Radeon R9 M390X, which makes use of a 28 nm design. AMD has clocked the core speed at 723 MHz. The GDDR5 memory runs at a speed of 1250 MHz on this specific model. It features 2048 SPUs as well as 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
Radeon HD 7870 XT		185 Watts
	Difference: 60 Watts (48%)

Memory Bandwidth

In theory, the Radeon HD 7870 XT should be 20% faster than the Radeon R9 M390X overall, due to its greater data rate. (explain)

Radeon HD 7870 XT		192000 MB/sec
Radeon R9 M390X		160000 MB/sec
	Difference: 32000 (20%)

Texel Rate

The Radeon R9 M390X should be a small bit (about 4%) better at AF than the Radeon HD 7870 XT. (explain)

Radeon R9 M390X		92544 Mtexels/sec
Radeon HD 7870 XT		88800 Mtexels/sec
	Difference: 3744 (4%)

Pixel Rate

The Radeon HD 7870 XT will be a lot (about 28%) better at anti-aliasing than the Radeon R9 M390X, and will be able to handle higher screen resolutions better. (explain)

Radeon HD 7870 XT		29600 Mpixels/sec
Radeon R9 M390X		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 maximum amount of data (in units of MB per second) that can be transferred past the external memory interface in a second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR 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 AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). 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 potential to reach the maximum fill rate.