Centrino's Better Battery

Centrino's clock frequencies are lower than those of the higher-end Pentium 4-M chips, but don't let the numbers fool you: The idea was to move the mobile market closer to the cell-phone model of always-on, always-connected access. It's still a ways off, but Intel realized it had to go back to the drawing board to address the power and connectivity issues. This means Centrino has to be as stingy with power as possible.

From the sparse amount of technical information Intel provided at last year's Microprocessor Forum, it seems the company's Israeli-based design team under Mooly Eden did not come up with a major, new wonder technology, but with something that seems to be a cross between a Pentium III and Pentium 4, plus many clever little tweaks to save power without sacrificing too much performance. Eden's team realized that every processor clock cycle costs valuable battery power, so it made sense to design Centrino for a high instructions-per-cycle rate, as it can do much work in only a few clock cycles. The result: This chipset has a shorter pipeline and runs at lower clock frequencies than the Pentium 4 series.

Tagging along with the CPU are two chipsets: the 855PM (Odem) and the 855GM (Montana-GM), which can be combined with the Southbridge ICH4-M, the mobile variant of the ICH-4. The 855PM is meant to be the link to a dedicated CPU via an AGP 4x port, while 855GM comes with Intel's own integrated 3D graphics (or, as we like to call it, 3D-decelerator). Both support DDR memory, have a mobile-optimized memory controller and communicate with the Centrino processor over its 400-MHz low-power processor system bus.

Tom's Hardware compared the performance of a 1.6-GHz Centrino to a 2.2-GHz Pentium 4-M inside two systems. Both had 256 MB of PC2-100 DDR SDRAM and the same IBM 20-GB Travelstar hard disks. The battery capacity of the Centrino system was 49 watt-hours, while the Asus L3C motherboard-based Pentium 4 system was 59 watt-hours. We tested three different scenarios: playing a DVD, running a presentation continuously and playing the demo game from 3D Mark 2001 SE. In each case, we recorded how long it took the units to run their batteries down. In each scenario, the Centrino lasted longer than the Pentium 4-M. If you factor in the operating time of both platforms with respect to their differing battery capacities, then the Centrino system gives you an operating time of roughly 20 minutes longer.

While Centrino satisfied us both on performance as well as battery life, it remains to be seen whether people will get used to the processor's high price tag and inability to outperform Pentium 4-M in terms of clock speed. Intel will be busy teaching people that it's not performance that counts, but the product of performance and battery life. For the typical business user, the SiSoft Sandra benchmark results show the Centrino is comparable to the Pentium 4-M in terms of arithmetic and multimedia processing.

Intel's strategy is to make wireless LANs ubiquitous, and that will play an important part of the push on Centrino. Battery life will become a very important issue, because you don't want to sacrifice your newly earned freedom for a regular trip to the next power outlet. With the balance of features and performance Intel achieves here, the company seems to be making headway on the road to always-on computing.