Radeon HD 4890 2GB vs Radeon R9 M295X

Intro

Compare all that to the Radeon R9 M295X, which features GPU clock speed of 750 MHz, and 4096 MB of GDDR5 RAM set to run at 1375 MHz through a 256-bit bus. It also features 2048 Stream Processors, 128 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M295X		125 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 65 Watts (52%)

Memory Bandwidth

Theoretically speaking, the Radeon R9 M295X is 41% quicker than the Radeon HD 4890 2GB overall, because of its higher data rate. (explain)

Radeon R9 M295X		176000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 51200 (41%)

Texel Rate

The Radeon R9 M295X is quite a bit (about 140%) faster with regards to AF than the Radeon HD 4890 2GB. (explain)

Radeon R9 M295X		96000 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 56000 (140%)

Pixel Rate

The Radeon R9 M295X will be much (approximately 50%) better at full screen anti-aliasing than the Radeon HD 4890 2GB, and also should be able to handle higher resolutions without slowing down too much. (explain)

Radeon R9 M295X		24000 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 8000 (50%)

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 max amount of information (in units of megabytes per second) that can be transferred over the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory speed. In the case of DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This figure is calculated by multiplying the total number of texture units by the core 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 applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.