Radeon HD 4870 2GB vs Radeon R9 M390X

Intro

Compare those specifications to the Radeon R9 M390X, which has core clock speeds of 723 MHz on the GPU, and 1250 MHz on the 4096 MB of GDDR5 memory. It features 2048 SPUs along with 128 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M390X		125 Watts
Radeon HD 4870 2GB		150 Watts
	Difference: 25 Watts (20%)

Memory Bandwidth

Theoretically speaking, the Radeon R9 M390X will be 39% quicker than the Radeon HD 4870 2GB overall, due to its higher data rate. (explain)

Radeon R9 M390X		160000 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 44800 (39%)

Texel Rate

The Radeon R9 M390X should be a lot (more or less 208%) better at anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon R9 M390X		92544 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 62544 (208%)

Pixel Rate

The Radeon R9 M390X will be a lot (more or less 93%) better at full screen anti-aliasing than the Radeon HD 4870 2GB, and will be capable of handling higher resolutions better. (explain)

Radeon R9 M390X		23136 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 11136 (93%)

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 largest amount of information (in units of megabytes per second) that can be transferred past the external memory interface in one second. The number is worked out by multiplying the interface width by its memory clock speed. If it uses DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.