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New Micron Process
AMD has made a lot of the fact that its new ‘Spider' platform, consisting of CPU, chipset and graphics was a smart and efficient design - hence it's ‘Smart Choice' tag line for the Spider launch. The new 3850 and 3870 definitely play their part in this running cooler and therefore quieter than their previous incarnations and unlike the previous gen HD 2900s, they only require a single power connector.
The reason for this is that for the 3000 series AMD has moved to a 55nm manufacturing process. As we know, shrinking down the size of each transistor brings with it a number of benefits. You can fit more chips onto a wafer, so that once the manufacturing process has been perfected you can get more chips, thus increasing supply. This lowers costs and enables prices to come down. You can also fit more transistors into the same space, though with the RV670 AMD has actually gone down from 700 million to 666m, resulting in a die size of 192 sq.mm.
It also means less heat and as you can see from the slide, it now has a power draw of 105W under full load, less than half of the HD Radeon 2900 XT. The end result is a cooler, quiet card to live with, which considering we should be looking at the same performance, is great. Both ATI and nVidia based graphics boards now feature generally quieter operation than previous generations, which is great to see, or rather hear.
Staying with power efficiency, AMD has also introduced technology on its ATI GPU's that's similar to the Cool ‘n Quiet on its CPUs, but up till now has only appeared on its mobile chips. It's called ATI PowerPlay for the Desktop. This introduces automatic power state adjustments depending on GPU activity, so under light usage parts of the GPU are shut down, so you're not drawing lots of power that you aren't using. Light gaming, essentially games that are CPU limited, (which is even the case for Source based games, like Team Fortress 2 and Half-Life 2: Episode 2, these days), will drop the power draw, while if you're playing a recent title, the chip will give it the full beans. It's a great idea and in this age of green issues, I'm amazed it's taken so long.
The basic architecture of the new cards is essentially the same as that of R600 - the HD 2900, and it still features 320 stream processors, split into 5 clusters of 64. As before there are 16 texture units and 16 Render Output Units (ROPs), the final part of the architecture that places the pixels on the screen. The programmable Tessalator Unit, as introduced on R600 is also present. The card is also now PCI Express 2.0 compliant, which means it can transmit data between it and the CPU at twice the speed as PCI Express 1. However, this is a non-issue as no card yet pushes the boundaries of PCI Express 1.