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I have a second PC, hooked up to a 650VA UPS. I recently upgraded its graphics card from a Radeon HD6850 to a Geforce GTX580. When I updated the Windows Experience Index thingy, the UPS started beeping like crazy, as if it had switched over to battery backup.

It seems to run fine, until I do anything graphics intensive like playing a game.

Is the PC itself trying to draw too much power for the UPS to handle? I was under the impression that my 650W power supply COULDN'T pull more than 650W, or is it just that it wasn't drawing a full load before the upgrade, and a 650VA UPS cannot handle 650W of power consumption?

Any advice would be greatly appreciated.

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It's an APC BK650-AS. After browsing their website, it appears I can use the "Surge only" socket. Won't have battery back up, but at least I'll have surge protection –  user1523244 Jul 19 '12 at 10:06
    
If that is indeed your model, the specs state that the max power output is 400W, which would explain the beeping. –  Oliver G Jul 19 '12 at 10:29
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Helpful to read the specifications on a bettery device before asking about it. –  Ramhound Jul 19 '12 at 11:24

2 Answers 2

up vote 1 down vote accepted

Advice

Get a new UPS with a larger output. I'd suggest at least a 1100VA unit, regardless of who makes it.

See, it works out roughly to the Volt-Amp rating, multiplied by 60%, equaling the wattage that the unit can support. Now, if you are going to have the computer and anything ELSE (like an external hard drive, or an LCD monitor) on the backup protection, then go with a 1250VA model.

That's my advice.

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The PSU can't (in theory, for a longer period of time, good brand ones can usually give more than they say) supple more than 650W on the DC side. There are conversion losses on top of this making a draw from the wall o, let's say 700w (because i have no idea which model your PSU is). The 650 VA UPS simply cant supply that much. Also in practice 650VA results in less than 650 W.

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