GeForce 8800 GTS (G80) 640MB vs Radeon HD 7770

Intro

Compare all that to the Radeon HD 7770, which uses a 28 nm design. AMD has clocked the core speed at 1000 MHz. The GDDR5 RAM works at a frequency of 1125 MHz on this model. It features 640 SPUs as well as 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
GeForce 8800 GTS (G80) 640MB		143 Watts
	Difference: 63 Watts (79%)

Memory Bandwidth

The Radeon HD 7770 should in theory perform a bit faster than the GeForce 8800 GTS (G80) 640MB overall. (explain)

Radeon HD 7770		72000 MB/sec
GeForce 8800 GTS (G80) 640MB		63360 MB/sec
	Difference: 8640 (14%)

Texel Rate

The Radeon HD 7770 is quite a bit (more or less 62%) faster with regards to AF than the GeForce 8800 GTS (G80) 640MB. (explain)

Radeon HD 7770		40000 Mtexels/sec
GeForce 8800 GTS (G80) 640MB		24624 Mtexels/sec
	Difference: 15376 (62%)

Pixel Rate

The Radeon HD 7770 should be a lot (more or less 56%) more effective at full screen anti-aliasing than the GeForce 8800 GTS (G80) 640MB, and will be capable of handling higher resolutions while still performing well. (explain)

Radeon HD 7770		16000 Mpixels/sec
GeForce 8800 GTS (G80) 640MB		10260 Mpixels/sec
	Difference: 5740 (56%)

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 megabytes per second) that can be transferred over the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core clock speed. 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 lots of 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.