John Martz wrote: > On Mon, Jun 22, 2009 at 2:55 PM, Clark Martin<cm...@sonic.net> wrote: >> The standard 3.5" & 5.25" drive power connector supplies +12V and +5V. >> 2.5" drives only need 5V so they would just use that power line. There >> is no 3.3V line on drive power cables. > > I'm not sure exactly what you mean. Yes, I think all the external > power supplies I've seen have only supplied at most +12v and +5v. > > But the SATA spec apparently specifies that pins 1 to 3 of a standard > 15 pin SATA power connector should supply 3.3 volts. I doubt any of > the current 3.5" drives actually depend on this, but it's apparently > part of the spec. > > I don't know about 2.5" drives, but I suspect they only need 5 volts > as you said. > > I've seen speculation that some of the solid state memory drives might > require the 3.3v supply, but it was just speculation. I really have no > idea why the SATA power connector is supposed to provide 3.3 volts to > some pins. But apparently that's what the spec says. > > (I thought about ... and immediately rejected ... poking around with a > volt meter in my SATA external enclosure's power connector to see what > it supplies to pins 1 to 3. Knowing me, I would be sure to short some > pins to ground and destroy a perfectly good enclosure. A geek's gotta > know his limitations ...)
I haven't looked into the SATA spec but I would think that in time the drives will use 3.3V for the logic in place of 5V. Most computer logic is going this way. A lower power supply voltage means not only lower power consumption but also faster speed. -- Clark Martin Redwood City, CA, USA Macintosh / Internet Consulting "I'm a designated driver on the Information Super Highway" --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com To unsubscribe from this group, send email to g3-5-list-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
