Radeon HD 4770 vs Radeon HD 4850 512MB

Intro

Compare those specifications to the Radeon HD 4850 512MB, which has a clock speed of 625 MHz and a GDDR3 memory frequency of 993 MHz. It also uses a 256-bit memory bus, and uses a 55 nm design. It features 800(160x5) SPUs, 40 TAUs, 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 4850 512MB		110 Watts
	Difference: 30 Watts (38%)

Memory Bandwidth

In theory, the Radeon HD 4850 512MB will be 24% quicker than the Radeon HD 4770 in general, because of its higher data rate. (explain)

Radeon HD 4850 512MB		63552 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 12352 (24%)

Texel Rate

The Radeon HD 4850 512MB should be just a bit (more or less 4%) better at anisotropic filtering than the Radeon HD 4770. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 1000 (4%)

Pixel Rate

The Radeon HD 4770 should be a little bit (approximately 20%) better at FSAA than the Radeon HD 4850 512MB, and able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 4770		12000 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 2000 (20%)

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 maximum amount of data (counted in megabytes per second) that can be transported past the external memory interface in one second. It is worked out by multiplying the card's interface width by the speed of its memory. If it uses DDR RAM, the result should be multiplied by 2 once 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 AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to its local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka 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, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.