Radeon HD 4790 vs Radeon HD 7770

Intro

Compare that to the Radeon HD 7770, which features a core clock speed of 1000 MHz and a GDDR5 memory frequency of 1125 MHz. It also uses a 128-bit bus, and uses a 28 nm design. It is made up of 640 SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 4790 should theoretically be quite a bit better than the Radeon HD 7770 in general. (explain)

Radeon HD 4790		102400 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 30400 (42%)

Texel Rate

The Radeon HD 7770 should be quite a bit (about 108%) faster with regards to texture filtering than the Radeon HD 4790. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 20800 (108%)

Pixel Rate

If running with high levels of AA 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 4790		9600 Mpixels/sec
	Difference: 6400 (67%)

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 (in units of MB per second) that can be moved over the external memory interface in one second. It's calculated by multiplying the bus width by the speed of its memory. If it uses DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.