Radeon HD 4870 1GB vs Radeon HD 7990

Intro

Compare those specs to the Radeon HD 7990, which comes with GPU clock speed of 950 MHz, and 3072 MB of GDDR5 memory set to run at 1500 MHz through a 384-bit bus. It also is comprised of 2048 SPUs, 128 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 1GB		150 Watts
Radeon HD 7990		375 Watts
	Difference: 225 Watts (150%)

Memory Bandwidth

Performance-wise, the Radeon HD 7990 should in theory be much better than the Radeon HD 4870 1GB overall. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4870 1GB		115200 MB/sec
	Difference: 460800 (400%)

Texel Rate

The Radeon HD 7990 should be a lot (approximately 711%) more effective at AF than the Radeon HD 4870 1GB. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 213200 (711%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 7990 is superior to the Radeon HD 4870 1GB, by a large margin. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4870 1GB		12000 Mpixels/sec
	Difference: 48800 (407%)

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 past the external memory interface in a second. The number is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

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