-------- Original Message -------- Subject: Re: [CentOS] Power-outage From: m.roth at 5-cent.us To: CentOS mailing list <centos at centos.org> Date: Friday, July 01, 2011 9:28:21 AM > Nicolas Thierry-Mieg wrote: >> Colin Coles wrote: >>> On Friday 01 July 2011 12:05, Timothy Murphy wrote: >>>> Any advice or suggestions gratefully received. >>> If you are thinking of the UPS route a caveat: I have several HP servers >>> and most of them will not work on cheap UPS's as they do not produce the >>> pure sine wave modern HP machines require but rather a crude stepped >>> voltage. >> perhaps naively, I'm surprised: doesn't this mean they put crappy PSUs >> in those servers? >> I thought decent PSUs were expected to deal with dirty input AC? > I agree. Esp. since, other than in datacenters, *most* electric power is > pretty crappy. > > mark "let's not discuss ComEd in Chicago" > I would have to disagree. They probably put high efficiency active PFC power supplies in the servers to save YOU money. You could buy a cheaper PSU that will not be as efficient and would thus cost you more in electric costs and create more heat (which would again cost you more in AC bills and reduce server density). The active PFC supplies are actually better at dealing with high/low voltages, however they do require actual AC power that conforms to a true sine wave. Newer/better UPS units output sine waves, cheaper or older UPS units may only output approximated (aka stepped) sine waves. Dell has done this in some of their boxes too, and I would expect to see it occur more often as more consumers are looking at 80+ and better certified PSUs.