Power-saving modes in Pentium IIIs go awol

Copperwhines continue to put Katmai amongst pigeons

Correspondence between Intel technical support staff and end users suggests that much-vaunted power saving modes in Pentium III Coppermine processors seem to have done a bunk. Data sheets that Intel is supplying on Coppermine Pentium IIIs state: "The Pentium III processor utilizes multiple low-power states such as AutoHALT, Stop-Grant, Sleep, and Deep Sleep to conserve power during idle times." But some of these states of deep sleep now seem to have turned into the dreaming state instead. In an exchange on Intel's own discussion group on the Pentium III, one user refers to these power states, which also formed part of the earlier processor, the Pentium II. In table eight in the spec sheets, one user says that the maximum core current is given for each power saving state and that the old, Katmai core, appears to show that each success state uses less current. However, he points out, Coppermine cores do not seem to have this ability, and cites comparisons between both Katmai and Coppermine which demonstrate his findings. He points out in a posting: "From these figures it can be seen that the Coppermines may "support" these power-saving modes, but since Sleep and Deep Sleep don't save any more power than Stop-Grant/Auto-Halt, the "support" is rather pointless. In the case of 600MHz in Deep Sleep, the power consumption of the Coppermine would be more than 2.5x the Katmai." He asks Intel if support for these power saving modes has been quietly dropped, or whether there is a mistake in the data sheets themselves. Now Intel has admitted that the numbers in its datasheet are correct, and give the following explanation: "While our manufacturing processes get smaller and smaller (.25 micron to .18 micron ) the widths of the channels between trace lines gets narrower. As a side effect, the current leakage is amplified." The reply implies that people contemplating using Coppermine processors swayed by power-saving issues had best think again. ®

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