Purchasing a UPS - please advise

[zyndell_apc]

This was originally posted on APC forums on 8/5/2014

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Hello,

A power surge during a thunderstorm recently fried my entire system and I would like to prevent that from happening again by purchasing a UPS. I am however not completely certain as to which model would be most suitable for me, so I am hoping that one of you experts would find a few minutes to help me out with a few questions.

What I would like to protect, is my home office equipment, including a quite powerful desktop gamer PC. I have calculated an approximate power consumption of 550W for the PC itself, but it's sitting behind a 1000W PSU. So just to be sure: using a 1000W PSU doesn't mean that it draws all that much power at all times, but only that it's capable of providing that much? Meaning, in my situation, going with .. let's say a theoretical consumption of 600W would be alright?

In addition to the desktop PC, there are a few other devices I would like to protect: 2x 26" screens (2x 40W), a router (10W), a laser printer (450W) and a sound system (200W). So my second question: does the "maximum output capacity" of a UPS only refer to the "backup protection", or does that also include the "surge protection" ?

To be a little bit more specific: I was looking to purchase the APC Back-UPS Pro 1500, 230V, Schuko, which has a max configurable power of 865W, and I wanted to hook up the PC, both screens and the router (total of estimated 690W) to the battery backup, and the printer and sound system (650W) to the surge protection. In the meantime, this UPS model also provides a solution for protecting the network, which I intend to use for my router as well.

Will this work? If not, please advise.

Thanks in advance!

[Techsplosion_apc]

This was originally posted on APC forums on 8/6/2014

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To answer your first question, a 1000w PSU will not be drawing 1000w at all times - power draw increases as usage increases. Idle power draw could be somewhere  between 100-200w, and depending on your setup I think your estimate of 600w is pretty good (unless you're running 3 SLI graphics cards and playing multiple games at max settings, you probably won't go over 600w ). It's always best to size larger, worst case scenario you end up with a slightly larger UPS that's giving you more runtime.

Secondly, "maximum output capacity" does refer to how much the UPS can output from its battery backup + surge outlets, equipment connected to the surge-only side doesn't count towards that.

The only extra thing you should check out are the power requirements of your PSU. It takes a BackUPS around 8-10ms to switch from online to on-battery mode - this isn't a problem with standard desktop computers, but if you have a high-end power supply that requires a faster transfer time to stay on it could cause issues. The other factor is a BackUPS doesn't produce a "pure" sine wave while on battery, it creates a stepped-sine wave. Again, not a problem with a standard desktop PC but it could cause issues with a high-end PSU that needs a pure wave - your PSU manufacturer/user manual should be able to let you know.

I'd wager that the BR/BX1500G would work fine, but it's always good to check just in case.

[zyndell_apc · Accepted solution]

This was originally posted on APC forums on 8/6/2014

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Thank you very much for your reply, that's exactly what I needed to hear .

As for the PSU ... I am using a OCZ ZX1000W, which is pretty high end (92% efficiency). I checked the manual and the manufacturer's homepage, but couldn't find any indications about its transfer time or whether or not it requires a pure sine wave. Google doesn't seem to know either, so I suppose I'll just have to try then .