Radeon HD 4870 512MB vs Radeon HD 7770

Intro

Compare that to the Radeon HD 7770, which comes with a GPU core clock speed of 1000 MHz, and 1024 MB of GDDR5 RAM set to run at 1125 MHz through a 128-bit bus. It also features 640 Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770		80 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 70 Watts (88%)

Memory Bandwidth

Theoretically, the Radeon HD 4870 512MB should perform a lot faster than the Radeon HD 7770 overall. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon HD 7770 will be much (approximately 33%) more effective at texture filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 10000 (33%)

Pixel Rate

The Radeon HD 7770 should be quite a bit (approximately 33%) faster with regards to AA than the Radeon HD 4870 512MB, and capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 4000 (33%)

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: Bandwidth is the largest amount of information (counted in MB per second) that can be transported over the external memory interface in a second. It is worked out by multiplying the bus width by its memory clock speed. If the card has DDR memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of ROPs by the the core speed of the card. 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 potential to get to the max fill rate.