SL-Enhanced CPUs: Power Misers, But Rare

The Mitac Micronote Performance Model 4021G/CT is the only notebook in this review that uses an SL-enhanced processor (33-MHz 486DX). It provides the second-longest battery life (4 hours, 9 minutes) among active-matrix color notebooks. The Mitac Micronote Lite Subnotebook Model 4010F and Sager NP440C subnotebooks also make use of SL-enhanced technology (25-MHz 486SX processors). The Model 4010F's battery life (2 hours, 57 minutes) is slightly below average for subnotebooks. The NP440C contains a passive-matrix color display that limits its battery life (1 hour, 55 minutes) in our Thumper 2 battery test.

Utilizing Intel's system management mode, the SL-enhanced technology provides the necessary power for applications while the system is conserving energy. Active power management turns hardware components on and off on an as-needed basis. SL-enhanced technology uses clock-throttling, where the CPU can distinguish between the amount of power needed to run at a lower clock frequency (e.g., for a word processing application) or at a higher clock frequency. Stop Clock lets the 486SL CPU operate at any frequency (from 0 MHz to the maximum), and Auto Idle automatically reduces the average power that a 486DX2 CPU consumes by as much as 10 percent.