In order to help the Radeon Xpress 200 go mobile, ATI has implemented a number of power-saving tricks, and they claim the chipset actually has lowest power requirements in the Intel-based mobile world. There are two versions of the north bridge, one called the RS400M built on a low-K 130nm fab process, and another at 110nm dubbed the RC410. Most RC410 designs will use only a single channel of memory in order to save costs. (Eventually, all of ATI's chipsets will make the move to 110nm.) Both flavors of the north bridge use a technique call DLCS, for Dynamic Lane Count Switching, to scale back the number of active PCI Express lanes when unneeded. ATI claims a power savings of up to 30% with this technique.
Interestingly enough, when paired with an ATI HyperMemory graphics chip, the 200M will also have a "HyperPath" capability, which is basically just overclocking the PCI Express connection in order to achieve higher throughput. Given how important a fast path to memory is on a HyperMemory card, this optimization could help perform as much as 10%, they say.
The folks at ATI are realistic but still somewhat bullish on the prospects of breaking Intel's "platformized" deadlock over mobile chipsets with the Centrino brand. The 200M works with the full gamut of Intel mobile CPUs, including the Pentium M, but the bulk of ATI's design wins will probably come in the entry-level "desktop replacement" segment, where the Mobile Pentium 4 reigns. The 200M will also be finding its way into a number of Celeron M-based laptops, as well.