Which UPS should I get ?

[SR45]

The system is not here yet, so its difficult to use the Calculator at this moment, but I would like to know if anyone has an idea what UPS from APC I should get for my new system with the below specs. I have a 750 APC back up now, but its over three years old.

Only need a 10 to 15 minute reserve

Was thinking of the new APC Back-UPS RS 1500 LCD ($ 249.00)

VelocityMicro Gamers Edge PCX
850 watt power supply
8800 GTX single card
680i eVGA motherboard
WD 250 gb hard drive 16 cache ( One hard drive only )
Integrated audio
E6700 core 2 duo
4 gigs of Corsair DDR2-800 ram
20x Lite On DVD ( Only one )
24 inch Dell LCD

No printer will be hooked into Back-Up

Thanks to anyone that may assist me on this

 

[BillParrish]

Well, one way to look at it is,

You have an 800W power supply. At worst it is (and I am really making it a crap supply so we will have plenty of headroom) 60% efficient, meaning that will take 800W x 1.60 = 1280 Watts from the wall if it was so inefficient and it was also putting out every last watt it was rated for, highly unlikely. But there it is.

1280W at 120V is about 10.6 amps it is also 1280VA assuming a power factor of 1 which you probally will not have, but with the overhead from above and the fact you probally are not going to ever be pulling more than 600Ws out of that supply, I would guesstimate, and thats all it is, that something in the 1200VA range would do fine.

So if that APC is rated for 1500VA you plenty good if its runtime at full output is in the range you are looking for.


oops didnt see the dell LCD hmm think I probally still ok look on the brick or the back of it and see what its wattage rating is and add it to the 1280, I would think you would still be in the ball park the the 1500VA as even my 600W of actual PC load is probally a little high. But check it out and if its a big concern go the next size UPS up at the most as you are already in the ball park.

 

[[Spectre]]

You do not size a UPS based on capacity of the power supply but on actual load.

And a UPS is rated for its output for a specific amount of time.

Most APC units are overpriced for what you get and Cyberpower, Tripp-Lite, etc offer better value.

 

[SR45]

Yes, that is what I was thinking, but wanted someone elses opinon before going to the retail route, talk with a non expert, and listening to he/she on the same subject to verify what is being said. You know those stores with employees that really don't know a heck of a lot about power back ups

 

[BillParrish]

You do not size a UPS based on capacity of the power supply but on actual load.

You may not, and you do what you want, but I can and its a valid and very very conservative way of doing it. It will always result in a large safety margin and as we are not talking a large amount of money, makes little difference. The end user apparently had no major concern with a high quality unit that, yes I agree, is probally way more than what is needed. But no engineer ever got fired for recommending something with a high margin of safety and meeting budget.

Oh wait are you saying the 800W supply is not sufficient? If so that is another story, and if true my calculations are worthless.

 

[SR45]

It's a 850 watt power ( Not 800 ) supply that will run just one 8800 GTX card not sli for a long time, which has been certified to run sli. Than upgrade the p/s to a 1200 or so by that time.


Got the APC 1500 VA Back-UPS XS instead of the RS, and all is well. Thanks guys