(EE hat on..) There's an irony here. The desktop PC power supply takes the 120vac line, turns it at once into DC, then switches that to make high-frequency AC, runs the AC into a transformer and rectifies the outputs of it. (That way a tiny cheap high-frequency xformer can be used instead of a big heavy 60 hz one.) But for an almost inconsequential amount of extra effort, a different initial DC voltage could be used, say 48vdc, so that (CHEAP) battery backup could be added to any PC. (EE hat off) If they did, of course, APC, BEST etc would have a hard time. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433