Radeon HD 4870 1GB vs Radeon HD 7990

Intro

Compare all of that to the Radeon HD 7990, which features a clock frequency of 950 MHz and a GDDR5 memory frequency of 1500 MHz. It also features a 384-bit memory bus, and makes use of a 28 nm design. It features 2048 SPUs, 128 TAUs, 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

Theoretically speaking, the Radeon HD 7990 should perform much faster than the Radeon HD 4870 1GB in general. (explain)

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

Texel Rate

The Radeon HD 7990 will be a lot (approximately 711%) more effective at texture filtering 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 running with high levels of AA is important to you, then the Radeon HD 7990 is a better choice, 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 max amount of data (measured in megabytes per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the card's bus width by its memory speed. If the card has DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.