Radeon HD 4770 vs Radeon HD 7790

Intro

Compare those specs to the Radeon HD 7790, which comes with a clock speed of 1000 MHz and a GDDR5 memory frequency of 1500 MHz. It also makes use of a 128-bit bus, and uses a 28 nm design. It is made up of 896 SPUs, 56 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4770		80 Watts
Radeon HD 7790		85 Watts
	Difference: 5 Watts (6%)

Memory Bandwidth

Theoretically, the Radeon HD 7790 should perform a lot faster than the Radeon HD 4770 in general. (explain)

Radeon HD 7790		96000 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 44800 (88%)

Texel Rate

The Radeon HD 7790 is quite a bit (approximately 133%) faster with regards to AF than the Radeon HD 4770. (explain)

Radeon HD 7790		56000 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 32000 (133%)

Pixel Rate

The Radeon HD 7790 is much (about 33%) faster with regards to anti-aliasing than the Radeon HD 4770, and also able to handle higher resolutions better. (explain)

Radeon HD 7790		16000 Mpixels/sec
Radeon HD 4770		12000 Mpixels/sec
	Difference: 4000 (33%)

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 data (in units of megabytes per second) that can be transferred over the external memory interface in one second. It's calculated by multiplying the interface width by the speed of its memory. In the case of DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, 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 number of texture map elements (texels) that can be applied in one second. This is calculated by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.