Radeon HD 4890 2GB vs Radeon R7 250

Intro

Compare that to the Radeon R7 250, which comes with a GPU core clock speed of 1000 MHz, and 1024 MB of GDDR5 memory running at 1150 MHz through a 128-bit bus. It also is comprised of 384 Stream Processors, 24 Texture Address Units, and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R7 250		65 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 125 Watts (192%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4890 2GB should be 70% faster than the Radeon R7 250 overall, due to its higher data rate. (explain)

Radeon HD 4890 2GB		124800 MB/sec
Radeon R7 250		73600 MB/sec
	Difference: 51200 (70%)

Texel Rate

The Radeon HD 4890 2GB should be quite a bit (approximately 67%) faster with regards to AF than the Radeon R7 250. (explain)

Radeon HD 4890 2GB		40000 Mtexels/sec
Radeon R7 250		24000 Mtexels/sec
	Difference: 16000 (67%)

Pixel Rate

The Radeon HD 4890 2GB should be quite a bit (more or less 100%) more effective at AA than the Radeon R7 250, and also should be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 4890 2GB		16000 Mpixels/sec
Radeon R7 250		8000 Mpixels/sec
	Difference: 8000 (100%)

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 (measured in megabytes per second) that can be transported past the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory speed. If the card has DDR RAM, the result should be multiplied by 2 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, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.