Radeon HD 4850 512MB vs Radeon HD 6790

Intro

Compare those specifications to the Radeon HD 6790, which makes use of a 40 nm design. AMD has set the core frequency at 840 MHz. The GDDR5 memory is set to run at a speed of 1050 MHz on this particular model. It features 800 SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 512MB		110 Watts
Radeon HD 6790		150 Watts
	Difference: 40 Watts (36%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6790 should be quite a bit faster than the Radeon HD 4850 512MB in general. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 70848 (111%)

Texel Rate

The Radeon HD 6790 is much (about 34%) more effective at AF than the Radeon HD 4850 512MB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 8600 (34%)

Pixel Rate

The Radeon HD 6790 will be a lot (approximately 34%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 512MB, and also capable of handling higher resolutions more effectively. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 3440 (34%)

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

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can 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 core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.