Intel "Santa Rosa" Centrino

The Centrino mobile brand is one of Intel's major success stories of the last few years, and it's had constant updates to keep pace with technology since its introduction in 2003. This latest revision is one of the most comprehensive yet. As ever, the new Centrino - technically Centrino Duo with its dual-core processor - comprises three modules, all of which need to be present for a notebook to qualify for the official Centrino label. The three modules in question are the processor, chipset and wireless module.

New processor

The new mobile versions of the Core 2 Duo processor receive a comprehensive set of tweaks. Most novel is Intel Dynamic Acceleration. This is a workaround to get maximum performance for the large number of single-threaded applications still around that don't benefit from dual cores. Games are among the primary guilty parties here and, with Intel's general attempt to court more gamers and enthusiasts, it's a canny move. Dynamic Acceleration technology works by detecting when one core is largely idle and the other is at 100% utilisation. In this situation, it can stop the clock of one core, while boosting the speed of the other above its nominal speed rating. Ordinarily, overclocking a mobile processor is taboo, since the extra power consumption will breach the thermal design of a chassis, leading to overheating problems. But with one core stopped - and thus consuming almost no power - the other's clock frequency can be increased while still keeping the total power consumption within the chip's 35W TDP (thermal design power) envelope. Concrete details of the extent of the IDA speed increase haven't been confirmed, but an Intel spokesperson told us that, essentially, the processor moves up to the next speed bin rating, so a 2.4GHz T7500 will temporarily clock itself up to 2.6GHz.

There are six new processor models. The four standard T-series offerings range from 1.8GHz to 2.6GHz, with either 2MB for the lowest-end T7100 or 4MB of Level 2 cache for the rest of the range; the maximum 4MB of Level 2 cache complement is unchanged from the previous mobile Core 2 generation. There are also two lower-power LV (low-voltage) offerings at 1.4GHz and 1.6GHz, plus some as-yet unconfirmed ULV (ultra-low voltage) variants.

The final major improvement is an increase in FSB (front side bus) speed, which rises from 667MHz to 800MHz. Maximum memory speed via the chipset is still limited to 667MHz, however, so the overall speed increase won't be as high as a uniform boost.

Processor power management

Power management has been further refined to keep increased clock speeds from pulling the processors over their TDP ratings. As well as processor clock speed, for the first time, the FSB speed can be dropped too. More subtle refinements include a system to allow the processor to deep-sleep for longer in the existing Enhanced Deeper Sleep stop-clocked state, by letting the chipset know the processor cache has been flushed so it doesn't need to wake it unnecessarily during "snoop" cycles.

On the chipset and supporting components side, Intel claims the total power savings across the platform for Santa Rosa can add up to over 2.5W. Almost 1W of that comes from the new but unlikely-to-be-used ability of the wired Ethernet connection to drop its speed to 100Mb/sec while running on battery. Nonetheless, that still represents a saving of over 1W, which in an average notebook can theoretically add around 20 to 30 minutes to the battery life.