Radeon HD 4750 vs Radeon HD 4770

Intro

Compare those specifications to the Radeon HD 4770, which has GPU clock speed of 750 MHz, and 512 MB of GDDR5 memory running at 800 MHz through a 128-bit bus. It also is comprised of 640(128x5) SPUs, 32 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4750		75 Watts
Radeon HD 4770		80 Watts
	Difference: 5 Watts (7%)

Memory Bandwidth

Both cards have exactly the same bandwidth, so theoretically they should have identical performance. (explain)

Texel Rate

The Radeon HD 4770 will be just a bit (approximately 3%) more effective at AF than the Radeon HD 4750. (explain)

Radeon HD 4770		24000 Mtexels/sec
Radeon HD 4750		23360 Mtexels/sec
	Difference: 640 (3%)

Pixel Rate

The Radeon HD 4770 is a small bit (about 3%) better at anti-aliasing than the Radeon HD 4750, and also should be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 4770		12000 Mpixels/sec
Radeon HD 4750		11680 Mpixels/sec
	Difference: 320 (3%)

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 max amount of information (counted in MB per second) that can be moved across the external memory interface within a second. It is worked out by multiplying the bus width by its memory clock speed. If it uses DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed per second. This figure is worked out 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 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 number of pixels the video card could possibly write to the 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 - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.