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I just asked this question where my PC may have been fried due to a power surge.

Now I'm browsing around and I'm curious what characteristics make a quality UPS? What should I be looking at? Should I be wary of the cheaper UPS's? Whats the difference between a $400 and a $40 UPS? I want to prevent future PCs from frying and a couple minutes of extra power might also be nice.

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Seems like a shopping question to me. –  Wuffers Feb 4 '11 at 22:11
    
@Wuffers: This question is on topic because it asks for general information about what to consider when buying a UPS, rather than for a specific product to be recommended. See meta.superuser.com/questions/2991/…. –  DragonLord Apr 20 '12 at 2:00

5 Answers 5

We are no supposed to give shopping advice here, but I have to admit Brand has alot to do with quality, APC makes the best consumer grade UPS's imho, I have used other brands like tripplite and chinese knock offs to my own detriment, the tripplite caught fire, the knock offs just plain fail to do the primary function of a ups, they dropped the load.

Other than that choose the correct size for your needs, a minimum of 650 watts for most Desktop PCs, 900 watt or above is better, depends on the run on battery time you need.

Also look for a APC UPS with the ability to connect a data cable (USB) to the PC so you can use APC powerchute software so the UPS can signal the OS shut down the PC before the battery runs out.

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Discussing qualities of a good UPS is not shopping advice in the discouraged sense (like "Buy this product, it's great!"). Referring to vendors might be, though. –  Daniel Beck Feb 4 '11 at 17:32
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Recommending brands and models is considered shopping advice here, posts get closed for that very reason here. In the faq is states that "a shopping or buying recommendation" is not what this site is about...superuser.com/faq...I know the OP did not ask, but to answer without it is near impossible. –  Moab Feb 4 '11 at 18:39

Size, warranty, reimbursement if your system gets fried are all easy to see on the box. If you want to get a bit more technical, then try and look for these items:

Total joules dissipated in the event of a surge. How much overvoltage can it ground before it has to let some through. No - it won't totally ground out a lightning strike, just part of it so be realistic. The higher it is, the more likely it can stop normal overvoltages.

Does it have EMI/RFI filtering to reduce line noise? Noise on the line causes strange hiccups on your system - corruptions, blue screens...

What is the waveform? Normal power is supposed to be a sine wave. Cheap UPS devices will create a square wave. The quick ramp up in power tends to overheat your power supply and the quick drop isn't so good either. Better UPS's use a modified wave like a trapezoid wave and the best and most expensive almost duplicate a sine.

Does it cut over to battery on brown outs and overvoltage or does it modify the power? If the UPS is better quality, on brown outs, it won't completely switch to battery, it just sips from the battery to make up the difference. On overvoltage, it tries to clip the surge.

There are other specs, if you are really interested, go to the various websites and look at their top of the line models to see the features.

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This link apc.com/support/service/equipment_protection_policy.cfm lists the maximum equipment replacement payout for APC UPS's. I'd say that that's as good a buying guide as any, at least when it comes to APC. –  Doug T. Feb 5 '11 at 16:16

More expensive UPS units tend to have a sine wave output rather than a square or modified square wave output. They also tend to use higher quality components and employ better QC. They often have full voltage regulation, protection you from brown-outs and other dirty power conditions rather than strictly power outages.

Some UPS units also have the capabilities to gracefully shutdown more than one system.

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There's some good, practical advice in this posting:

How to choose a UPS / calculate power for a new PC

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This link is a really good overview of the different kinds of UPS's.

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