Radeon HD 4650 1GB vs Radeon HD 7990

Intro

Compare all that to the Radeon HD 7990, which features a core clock speed of 950 MHz and a GDDR5 memory speed of 1500 MHz. It also uses a 384-bit memory bus, and uses a 28 nm design. It is made up of 2048 SPUs, 128 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 1GB		55 Watts
Radeon HD 7990		375 Watts
	Difference: 320 Watts (582%)

Memory Bandwidth

Theoretically, the Radeon HD 7990 should perform much faster than the Radeon HD 4650 1GB overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 553600 (2471%)

Texel Rate

The Radeon HD 7990 will be much (more or less 1167%) faster with regards to AF than the Radeon HD 4650 1GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4650 1GB		19200 Mtexels/sec
	Difference: 224000 (1167%)

Pixel Rate

The Radeon HD 7990 is much (about 1167%) faster with regards to full screen anti-aliasing than the Radeon HD 4650 1GB, and also should be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4650 1GB		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: Bandwidth is the maximum amount of information (counted in megabytes per second) that can be transported across the external memory interface in one second. It's worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR type memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.