Radeon HD 4650 1GB vs Radeon HD 7990

Intro

Compare those specs to the Radeon HD 7990, which features a GPU core clock speed of 950 MHz, and 3072 MB of GDDR5 RAM running at 1500 MHz through a 384-bit bus. It also features 2048 Stream Processors, 128 Texture Address Units, and 32 ROPs.

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 in general. (explain)

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

Texel Rate

The Radeon HD 7990 is quite a bit (approximately 1167%) better at anisotropic filtering 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 will be a lot (about 1167%) faster with regards to full screen anti-aliasing than the Radeon HD 4650 1GB, and also will be able to handle higher resolutions while still performing well. (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 data (in units of MB per second) that can be moved over the external memory interface in a second. It is worked out by multiplying the bus width by its memory clock speed. If the card has DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the clock speed of the card. 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 many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.