Radeon HD 7870 vs Radeon R9 M290X

Intro

Compare all that to the Radeon R9 M290X, which comes with a GPU core clock speed of 850 MHz, and 4096 MB of GDDR5 memory running at 1200 MHz through a 256-bit bus. It also is comprised of 1280 Stream Processors, 80 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M290X		100 Watts
Radeon HD 7870		175 Watts
	Difference: 75 Watts (75%)

Memory Bandwidth

Both cards have the exact same bandwidth, so theoretically they should have the same performance. (explain)

Texel Rate

The Radeon HD 7870 should be a small bit (about 18%) faster with regards to AF than the Radeon R9 M290X. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon R9 M290X		68000 Mtexels/sec
	Difference: 12000 (18%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7870 is the winner, not by a very large margin though. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon R9 M290X		27200 Mpixels/sec
	Difference: 4800 (18%)

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 information (counted in megabytes per second) that can be transported over the external memory interface in a second. It's calculated by multiplying the card's bus width by its memory speed. If the card has DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.