900w UPS enough to power or shut down a computer with a 850w power supply?

[jcfili]

Hey guys i need your help!

So summer is coming and I'm afraid of blackouts it could be for 1 min or maybe when you have AC in all rooms on at the same time and my goal is so the UPS shuts my PC down safe so i don't lose data.
I'm trying to buy a UPS (uninterruptible power supply) for my build that has a 850w power supply. I'm was thinking on a UPS with 900w. is this ok? or should i get a UPS with more wattage? ..remember I just want to shut down the pc

 

[GhislainG]

It will be fine as long as your PC doesn't draw 850W.

 

[JackNaylorPE]

Does your PSU have active PFC ?....most do.

Learn why most UPS won't work

http://www.dougv.com/blog/2010/03/01/active-pfc-enabled-psus-are-not-compatable-with-most-low-end-ups/

More here:

http://www.tomshardware.com/news/ocz-ups-battery-backup,7489.html

For a 850 w PSU, you'll want a 1500 VA unit..... will give you 10 minutes at about 70% PSU load

http://www.frozencpu.com/products/8914/psu-414/PC_Power_and_Cooling_Pro-Source_-_1500_VA_-_High_Output_Uninterruptible_Power_Supply_-_PPCUPSPS1500.html

 

[BulletTony]

Hey,


The fact that your power supply is 800W max doesn't mean it will actually consume that much. Most likely it will operate at no more than 400W. You would be okay with a 900W power supply. Most likely the 900 you talk about is a Back-UPS 900 or something similar. I wouldn't recommend going with any of those units for a good PC that has important work on it. The Back-UPSs don't output a sine wave and aren't very good for high end equipment. Get yourself a minimum of a Smart-UPS 1000 if you want dependable protection. The Smart-UPSs output a sine wave and offer much better power filtering and protection. If you'd like to have a little more run time, get yourself a Smart-UPS 1500. The 1500 will definitely support the power supply and any small appliances you have to go along with it. It's a data center unit. Doesn't make sense to spend money on poor protection.

 

[jcfili]

thank you guys and I forgot to post the System Configuration.... mine is

Asus Rampage II extreme
850w power supply FX
ATI5870
1 hd
i7 920

 

[GhislainG]

That system draws less than 400W at peak. Therefore a 900W UPS (1500 VA) is fine.

 

[jcfili]

Best answer selected by jcfili.