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Old 03-13-2013
Digerati Digerati is offline
Join Date: Jan 2011
Location: Nebraska, USA
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Originally Posted by McSteel
They're mostly 220V-only because of a slim Graetz bridge (usually 4A/600V) and PFC/primary transistors.
I suspect you are right, but I also note a big reason they are mostly 220V is simply because the EU mandated it for all EU member countries. Non-PFC PSUs on the higher voltage grids were too inefficient, and often destabilizing.

since > 500W 220V-only models are also rare.
Ummm, huh? You lost me there. Were you referring to non-universal input power supplies? A quick search of UK and European parts sites finds lots of PSUs bigger than 500W. The PSU power rating is determined by it's output voltage - not power consumed at the wall and the ATX Form Factor standard is the same the world around with 3.3VDC, 5VDC, and 12VDC outputs.

Nevertheless, I highly doubt a computer running in a 230VAC environment will be of much use if the voltage drops to those low levels, unless the monitors, and all the network equipment are on UPS too.
Originally Posted by Beto Garcia
I checked the APC Back-UPS XS 1500 and itís very similar to the APC BR1500G BACK-UPS Pro 1500. Can anyone tell me the differences and / or pro-cons between the two? Is its operation silent?
I think XS is the designation for the previous version as the specs are virtually identical otherwise (my XS is 3 years old). The one big difference I see is the total recharge time is twice as fast with the newer version but that is not really an issue, unless you have multiple, back to back extended power outages that prevent a full recharge after each power restoral. You can operate your computer just fine while the batteries are charging - you will just have less runtime should you lose power while still charging.

They are totally silent when all is good. However, when you lose power, many UPS will start yelling (beeping) at you. Some UPS let you silence the alarm - some irritatingly don't. Some UPS also have internal cooling fans that sadly, over the years, can develop noisy bearings.
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