Not sure if this helps, but my sister's machine had a similar problem - any time a powered USB hub was plugged in, her machine would refuse to boot. Never did figure out why. -Randy On 11/13/06, Howard Winter wrote: > I tried building a device into a PC which was powered from the +5V line on one of the disk drive power connectors, and found that it was very > unreliable in starting up - more often than not it didn't! > > So I put a meter on the connector and found that when the PSU has mains connected, but is turned off, there was 1.8V on the 5V line, so powering > the PC down and up does not power the device I mentioned down properly. From cold it seems to work if you connect the power lead and then press > the power-button within a couple of seconds - more than that and it locks up the device. > > I tried another PSU and that was showing 0.8V and had the same problem. I know there is a separate 5V Standby supply, but I would have thought > that the main 5V should drop to zero when power is off, shouldn't it? > > Has anyone else encountered this? Am I likely to find a PSU that does behave "properly"? > > If not I'll have to use the +12V and put my own 5V regulator in-line, which will be annoying but will solve it (the +12V line does drop to zero). > > Cheers, > > > Howard Winter > St.Albans, England > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- -Randy Glenn Computer Eng. and Mgt. Year V, McMaster University Regional Student Representative, IEEE Canada randy.glenn-at-gmail.com - glennrb-at-mcmaster.ca randy.glenn-at-computer.org - randy_glenn-at-ieee.org http://www.randyglenn.ca -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist