Radeon HD 4750 vs Radeon HD 7990

Intro

Compare those specifications to the Radeon HD 7990, which features a core clock speed of 950 MHz and a GDDR5 memory speed of 1500 MHz. It also makes use of a 384-bit memory bus, and makes use of a 28 nm design. It features 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 4750		75 Watts
Radeon HD 7990		375 Watts
	Difference: 300 Watts (400%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7990 will be 1025% quicker than the Radeon HD 4750 in general, due to its greater data rate. (explain)

Radeon HD 7990		576000 MB/sec
Radeon HD 4750		51200 MB/sec
	Difference: 524800 (1025%)

Texel Rate

The Radeon HD 7990 is much (approximately 941%) better at texture filtering than the Radeon HD 4750. (explain)

Radeon HD 7990		243200 Mtexels/sec
Radeon HD 4750		23360 Mtexels/sec
	Difference: 219840 (941%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7990 is superior to the Radeon HD 4750, by far. (explain)

Radeon HD 7990		60800 Mpixels/sec
Radeon HD 4750		11680 Mpixels/sec
	Difference: 49120 (421%)

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 largest amount of information (in units of MB per second) that can be transported over the external memory interface within a second. The number is worked out by multiplying the bus width by its memory clock speed. If the card has DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster 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 texture map elements (texels) that are applied in one second. This figure is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics 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 that the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.