Radeon HD 4850 512MB vs Radeon HD 7770

Intro

Compare those specifications to the Radeon HD 7770, which comes with a core clock speed of 1000 MHz and a GDDR5 memory speed of 1125 MHz. It also makes use of a 128-bit memory bus, and makes use of a 28 nm design. It is comprised of 640 SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770		80 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 30 Watts (38%)

Memory Bandwidth

As far as performance goes, the Radeon HD 7770 should in theory be a small bit better than the Radeon HD 4850 512MB overall. (explain)

Radeon HD 7770		72000 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 8448 (13%)

Texel Rate

The Radeon HD 7770 should be a lot (about 60%) better at AF than the Radeon HD 4850 512MB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 15000 (60%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7770 is a better choice, and very much so. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 6000 (60%)

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 information (measured in MB 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. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, 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 texture units of the card by the core clock speed of the chip. The better the texel rate, the better the graphics 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 number of pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka 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, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.