Radeon HD 4650 512MB vs Radeon HD 7990

Intro

Compare that to the Radeon HD 7990, which features core clock speeds of 950 MHz on the GPU, and 1500 MHz on the 3072 MB of GDDR5 memory. It features 2048 SPUs along with 128 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 7990		375 Watts
	Difference: 320 Watts (582%)

Memory Bandwidth

The Radeon HD 7990 should theoretically perform much faster than the Radeon HD 4650 512MB in general. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 560000 (3500%)

Texel Rate

The Radeon HD 7990 will be quite a bit (more or less 1167%) better at AF than the Radeon HD 4650 512MB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 224000 (1167%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 7990 is a better choice, and very much so. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 56000 (1167%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of data (in units of megabytes per second) that can be moved over the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better 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 processed per second. This number is calculated 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 graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to its local memory per 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 output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.