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UPS capacity required for high-end PSU

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October 18, 2011 8:50:07 AM

My goal is to understand if my existing UPS can accommodate a high-end PSU, or if I should set my sights to a relatively lower end PSU. I want to know what my options are.

My existing UPS is a Kebos PowerGarde 1200VA. The output VAC is 220VAC+/-10% (auto sensing). See here: http://www.kebostech.net/product/category/2/4/8/12.

I plan to upgrade my PSU to an Antec HPC 1200W. See here: http://blog.antec.com/power-supplies/technical-finesse-....

Questions:

1. Will my existing UPS be able to handle this new PSU?

2. The output of the UPS is still 220VAC+/-10%. Does it actually matter that it has a maximum capable load of 1200VA?

3. What's the point in saying (does it really matter) that a UPS can handle 1200VA vs. 600VA, etc., if the output VAC is still 220VAC+/-10%?

4. Should I get a (relatively) lower end PSU that my UPS can handle?
October 18, 2011 8:55:36 AM

your UPS can handle the PSU, In case you have a power outage, your backup would just deplete faster, depending on the current draw of your PC itself.
at my former job we had a server running with a similar UPS, never had issues.
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a b ) Power supply
October 18, 2011 8:58:14 AM

I dont think it would matter much. Only your backup time would go down or up, depending on what your PC's total power usage is. Don't look at your PSU, just calculate what your total power consumption is of the PC.

But i can say that your UPS would be able to handle your PC.
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October 18, 2011 9:39:12 AM

Thank you, Admir00 and hell_storm2004, for the feedback. This answers my questions 1 and 4.

Any thoughts concerning the other two questions? I couldn't find anything on Google that comes close to answering these questions.
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Best solution

a b ) Power supply
October 18, 2011 9:53:45 AM

Well, i am not that good with electrics, but i will give it a shot.

You PC does not know where the power is coming from, all it needs is the power. So when you normally connect the PC to the wall, it delivers a power of 220V. So the output of the UPS also has to be the same to make the PC work. Like in my country the normal specification is 220V@60Hz. In US i think it is 110V@50Hz.

The 1200VA is the maximum rating of power it can handle. In this case your PC. Look up Volt-Ampere and you may have some idea.
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October 18, 2011 2:37:03 PM

hell_storm2004 -- your insight makes a lot of practical sense! Thank you so much.

Relationship of VA to Wattage: I found this item, and a discussion about the power factor which explains why there is no exact match between the two, that might be useful to anyone else who might have questions about this -- http://www.powerstream.com/VA-Watts.htm.
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October 18, 2011 2:37:49 PM

Best answer selected by engr_jpo.
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October 19, 2011 12:49:56 AM

UPS's have two ratings, they like to publish the VA rating though because it sounds better. BUT, you need to check what the maximum wattage rating of the UPS is as well. A 1200 watt PSU will NOT consume 1200 watts unless the system you built DRAWS 1200 watts. That is it's maximum rating. You HAVE to build your system based on the demands of your system build, not just any old number (of course though you can plan for the future). Understand what I am saying again. Just because you put an 800 watt power supply in a system doesnt mean you will draw 800 watts from the wall/UPS. Your system components must draw that amount of power from the power supply for it to make that demand subsequently to the wall/PSU (minus inefficiencies in power conversion of course). Now, the average low grade Kebos or similar UPS even at 1200VA will not have anywhere near that in watts of supported continuous draw. Maybe in the 5-600 watt range if that. What that means is the the batteries will support that draw for a longer time then say a 600VA UPS which might for instance support a 3-450 watt draw.

For instance, an overclocked i7 first generation with maybe 6-10 hard drives and a reasonable set of GPUs will draw around 300 watts at idle and may draw up to 600 watts while gaming full tilt. You need to have a PSU ready for draw and likewise a UPS able to handle that maximum load should the power drop while gaming.

Dont forget to count the draw of any other attached units like monitor, speakers, etc. And please dont attach laser printers to UPS's, that is very bad.

Hope that clears a little up for you.
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