Radeon HD 7990 vs Radeon R9 M275X

Intro

Compare all of that to the Radeon R9 M275X, which features GPU core speed of 900 MHz, and 2048 MB of GDDR5 memory set to run at 1125 MHz through a 128-bit bus. It also is comprised of 640 Stream Processors, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M275X		50 Watts
Radeon HD 7990		375 Watts
	Difference: 325 Watts (650%)

Memory Bandwidth

Theoretically, the Radeon HD 7990 should perform a lot faster than the Radeon R9 M275X in general. (explain)

Radeon HD 7990		576000 MB/sec
Radeon R9 M275X		72000 MB/sec
	Difference: 504000 (700%)

Texel Rate

The Radeon HD 7990 is a lot (about 576%) more effective at AF than the Radeon R9 M275X. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon R9 M275X		36000 Mtexels/sec
	Difference: 207200 (576%)

Pixel Rate

The Radeon HD 7990 is a lot (about 322%) more effective at FSAA than the Radeon R9 M275X, and will be capable of handling higher screen resolutions better. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon R9 M275X		14400 Mpixels/sec
	Difference: 46400 (322%)

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 max amount of data (counted in megabytes per second) that can be moved across the external memory interface within a second. It is worked out by multiplying the bus width by the speed of its memory. In the case of DDR type RAM, it must 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 amount of texture map elements (texels) that can be applied in one second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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 - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.