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UPS. VA rating and wattage

post #1 of 11
Thread Starter 
Looking to buy uninterrupted Power Supply.
Read that it is better to go with the VA (volt amp) rating, rather than wattage rating.
Aren't they essentially the same? I mean, watt = Voltage x Amp.
So, watt rating should equal VA rating, right?

If my PC draws 1000w as measured by Kill-a-watt from the wall socket, what is the minimum rating on UPS I should get?
Edited by lesterhung - 5/1/11 at 12:11am
post #2 of 11
no less then a 1200 watt UPS id recommend higher if your pc takes 1000watts alone
because you would want your monitor maybe speakers connected to it as well
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post #3 of 11
I'm no expert on UPS, as I've just started looking at getting them myself lately. But from what I've read VA rating is superior, becaose of PFC, for example if you are running a PFC of .5 (not likely but it can happen) Watt = .5 * VA = 1/2 of what you'd expect.

In general your PFC will probably be closer to .99, but to be safe I'd say that you might want to leave yourself a little extra bump unless you have the equipment to test.
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post #4 of 11
Quote:
Originally Posted by ocpokey;13338564 
I'm no expert on UPS, as I've just started looking at getting them myself lately. But from what I've read VA rating is superior, becaose of PFC, for example if you are running a PFC of .5 (not likely but it can happen) Watt = .5 * VA = 1/2 of what you'd expect.

In general your PFC will probably be closer to .99, but to be safe I'd say that you might want to leave yourself a little extra bump unless you have the equipment to test.

True, for your PC anyway. Non-PFC PSUs have a power factor of .5-.65, passive PFC is .7-.85, and active PFC is .95-.99. Most good PC PSUs have active PFC.

However, monitors and TVs, phone chargers, speakers, and just about anything that pulls less than 100W, will not have PFC and will have a power factor of .5-.65. So the VA rating for a UPS is very important.
post #5 of 11
No Ordinary PC would ever pull 1000W. Not even a 5GHz 2600k with 580's in sli.

All said yeah go with a bigger one. You always need a bit of headroom but dont go over the top because the efficiency may drop. Whats the battery size if i may ask?
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post #6 of 11
I Have an enterprise class Line-Interactive APC Smart-UPS for my servers and I know that it is 2200VA but it only has a max output of ~1900 Watts so you should always get one with a higher VA than the watt output needed because of the PFC. I think :S
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post #7 of 11
Thread Starter 
Mine PS has active PFC
post #8 of 11
Thread Starter 
Quote:
Originally Posted by Gothiq;13340495 
No Ordinary PC would ever pull 1000W. Not even a 5GHz 2600k with 580's in sli.

All said yeah go with a bigger one. You always need a bit of headroom but dont go over the top because the efficiency may drop. Whats the battery size if i may ask?
My PC is not Ordinary.
Its going to have 4 power hungry GPUs
post #9 of 11
Your pc draws a 1000w? are you powering the neighbourhood with it? Are you sure this is correct?
Why are you looking to get one? Do you have brown out problems, dirty power or are do you have important work to save during a black out?
Edited by Spooony - 5/1/11 at 11:56am
post #10 of 11
Thread Starter 
Quote:
Originally Posted by Spooony;13342516 
Your pc draws a 1000w? are you powering the neighbourhood with it? Are you sure this is correct?
Why are you looking to get one? Do you have brown out problems, dirty power or are do you have important work to save during a black out?
4x 6990 will easily be over 1000w.
I am tired of those flickering power that puts out the PC
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