[LINK] How many Newspapers does it take to build Ayers Rock?
dlochrin at d2.net.au
Wed May 13 21:05:11 EST 2009
On Wednesday 13 May 2009 13:44, Glen Turner wrote:
> Electricity-wise you're saving what [with an X-terminal] over a
> typical corporate client PC? Certainly the loss of a hard disk.
> Maybe the move from a Pentium to a Atom class of CPU. But
> exactly those savings would be made by using a Atom-class
> desktop with flash disk.
I was writing specifically about electrical power requirements. But there's no reason why an X-terminal can't use a fanless low-end Intel processor with no hard drive and embedded Linux if that's a better cost option.
I don't have time to comprehensively research the energy savings, but here's one comparison I just happen to know about. My HP d530 "small form factor" desktop requires 185 watts according to the Technical Reference, whereas the NCD 900-series thin client requires only 26 watts (both figures do not include the monitor). These days a diskless Linux-based thin client would probably be a better way to go.
And you'd have to factor in the energy saved with lower (much lower!) support requirements.
> DC [power] is bad news. Getting rid of all those conversion costs
> sounds really attractive, until you actually do it and realise that the
> higher transmission losses of DC have eaten all of the savings.
> And worse, that higher loss --> higher current --> thicker cabling
> and the whole exercise turns insanely expensive and using
> CO2-expensive materials.
OK, I think you've convinced me.
> So we're headed back to AC as the preferred power source for
> networking equipment, [...]
> What will be different this time around is that the efficiency of the
> power supply will be required to be high, and that cheats like low
> power factors will be removed by benchmark specifications.
A low power factor won't affect the efficiency of the equipment much. The power factor of a compact fluorescent lamp (CFL) is around 0.6 and they're still being used to phase out incandescent lamps; in fact AS/NZS 4847.2-2008 only requires a minimum power factor of 0.55.
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