Radeon HD 4770 vs Radeon HD 4870 1GB

Intro

Compare those specs to the Radeon HD 4870 1GB, which features a core clock speed of 750 MHz and a GDDR5 memory speed of 900 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4770		80 Watts
Radeon HD 4870 1GB		150 Watts
	Difference: 70 Watts (88%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 1GB should perform quite a bit faster than the Radeon HD 4770 in general. (explain)

Radeon HD 4870 1GB		115200 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 64000 (125%)

Texel Rate

The Radeon HD 4870 1GB will be a lot (approximately 25%) better at anisotropic filtering than the Radeon HD 4770. (explain)

Radeon HD 4870 1GB		30000 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 6000 (25%)

Pixel Rate

Both cards have the exact same pixel fill rate, so in theory they should be equally good at at anti-aliasing, and be capable of handling the same screen resolutions. (explain)

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 MB per second) that can be transported past the external memory interface within a second. The number is calculated by multiplying the card's interface width by its memory speed. In the case of DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines 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 also depends on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.