Radeon HD 4870 2GB vs Radeon R7 250

Intro

Compare those specifications to the Radeon R7 250, which has GPU clock speed of 1000 MHz, and 1024 MB of GDDR5 RAM set to run at 1150 MHz through a 128-bit bus. It also is made up of 384 SPUs, 24 TAUs, 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 4870 2GB		150 Watts
	Difference: 85 Watts (131%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 2GB should be 57% quicker than the Radeon R7 250 overall, because of its greater data rate. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon R7 250		73600 MB/sec
	Difference: 41600 (57%)

Texel Rate

The Radeon HD 4870 2GB will be a lot (approximately 25%) more effective at AF than the Radeon R7 250. (explain)

Radeon HD 4870 2GB		30000 Mtexels/sec
Radeon R7 250		24000 Mtexels/sec
	Difference: 6000 (25%)

Pixel Rate

The Radeon HD 4870 2GB will be much (about 50%) better at FSAA than the Radeon R7 250, and also should be capable of handling higher resolutions while still performing well. (explain)

Radeon HD 4870 2GB		12000 Mpixels/sec
Radeon R7 250		8000 Mpixels/sec
	Difference: 4000 (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 maximum amount of data (in units of megabytes per second) that can be transported over the external memory interface within a second. It is calculated by multiplying the interface width by its memory clock speed. If the card has DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better 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 are processed in one second. This figure is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics 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 that the graphics card could possibly write to its local memory in a 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 - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.