Radeon HD 6990 vs Radeon R9 M395X

Intro

Compare those specs to the Radeon R9 M395X, which has a core clock speed of 723 MHz and a GDDR5 memory speed of 1250 MHz. It also features a 256-bit memory bus, and uses a 28 nm design. It is made up of 2048 SPUs, 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 6990		375 Watts
	Difference: 250 Watts (200%)

Memory Bandwidth

In theory, the Radeon HD 6990 should be quite a bit faster than the Radeon R9 M395X in general. (explain)

Radeon HD 6990		320000 MB/sec
Radeon R9 M395X		160000 MB/sec
	Difference: 160000 (100%)

Texel Rate

The Radeon HD 6990 will be much (more or less 72%) faster with regards to AF than the Radeon R9 M395X. (explain)

Radeon HD 6990		159360 Mtexels/sec
Radeon R9 M395X		92544 Mtexels/sec
	Difference: 66816 (72%)

Pixel Rate

The Radeon HD 6990 will be quite a bit (approximately 130%) better at full screen anti-aliasing than the Radeon R9 M395X, and also will be capable of handling higher screen resolutions more effectively. (explain)

Radeon HD 6990		53120 Mpixels/sec
Radeon R9 M395X		23136 Mpixels/sec
	Difference: 29984 (130%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of information (measured in MB per second) that can be moved over the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. In the case of DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, 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 number of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher the texel rate, the better the card will be at 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 that the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.