Radeon HD 4830 1GB vs Radeon HD 4850 512MB

Intro

Compare those specs to the Radeon HD 4850 512MB, which features GPU clock speed of 625 MHz, and 512 MB of GDDR3 RAM set to run at 993 MHz through a 256-bit bus. It also is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4830 1GB		95 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 15 Watts (16%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 512MB will be 10% faster than the Radeon HD 4830 1GB overall, because of its greater data rate. (explain)

Radeon HD 4850 512MB		63552 MB/sec
Radeon HD 4830 1GB		57600 MB/sec
	Difference: 5952 (10%)

Texel Rate

The Radeon HD 4850 512MB will be quite a bit (more or less 36%) faster with regards to texture filtering than the Radeon HD 4830 1GB. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 4830 1GB		18400 Mtexels/sec
	Difference: 6600 (36%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 4850 512MB is a better choice, though not by far. (explain)

Radeon HD 4850 512MB		10000 Mpixels/sec
Radeon HD 4830 1GB		9200 Mpixels/sec
	Difference: 800 (9%)

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 (in units of megabytes per second) that can be transferred past the external memory interface in one second. It is calculated by multiplying the bus width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. 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 number of texture map elements (texels) that are processed per second. This is worked out by multiplying the total number of texture units by the core clock 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.