question about ups voltage for backup power supply


Dec 8, 2006
i have chosen the APC BE650R 650 VA 390 Watts 8
Outlets UPS for my computer.

my comp has a 700w psu, and i expect it will routinely
be in 500-550w area for power use.

my purpose with the apc is only to serve as short
lived backup power for a few mins max in case the
power goes out, and to protect from surges and spikes.
i do not intend to use it for any sort of sustained

i had someone tell me that the APC BE650R 650 VA 390
Watts 8 Outlets UPS i am considering will not be
sufficient. in his words: " When you try to draw too
much power from a battery backup unit, it'll trip the
circuit breakers (or melt some leads) in the backup

my intention in buying the apc is only to give myself
a min or two of power in the event of a power outage
in the house, so that i can shut my system off, and
also to protect again power spikes or surges. the
price of apc ups's above 390 watts get pretty
high--btwn $150-450, which is pretty steep.

is his advice accurate, and should i pony up for the
higher wattage units?

someone at tom's hardware forums countered that
earlier response, claiming:

"That UPS won't give you a lot of up time, but it is
fine for protecting against short (1-2 minute) outages
and it definitely won't melt down or anything crazy.
Sounds to me like it meets your planned need. "

so, before i order, i need to know- which is it?


here are my specs (lite on sata drive not included since newegg doesn't have it):

LIAN LI PC-7B plus II Black Aluminum ATX Mid Tower Computer Case - Retail

Seagate Barracuda 7200.10 ST3320620AS (Perpendicular Recording Technology) 320GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM

eVGA 768-P2-N831-AR GeForce 8800GTX 768MB GDDR3 PCI Express x16 HDCP Video Card - Retail

Creative Sound Blaster X-Fi XtremeGamer 70SB073A00000 7.1 Channels PCI Interface Sound Card - Retail

OCZ GameXStream OCZ700GXSSLI ATX12V 700W Power Supply - Retail

APC BE650R 650 VA 390 Watts UPS - Retail

CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400 - Retail

EVGA 122-CK-NF68-AR LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard - Retail

Intel Core 2 Duo E6600 Conroe 2.4GHz LGA 775 Processor Model BX80557E6600 - Retail


Dec 16, 2006
I am running a system with similar specs but with an Enermax Galaxy 1000watt PSU.

My APC Back-UPS LS 700 wouldn't handle it without tripping the overload alarm. I ended up buying a much more expensive APC UPS.

Just be careful ordering some of the highend UPS. Some of them require a 20amp power outlet. I had to rewire the power outlet in my room to make mine work.


Dec 8, 2006
and that one has 410 watts? i am quite the noob here- what do you mean by "tripping the overload alarm"? was the ls7000 damaged or unable to power your system at all when the power in your home went off?

looking at the prices of some the more power apc ups units is pretty daunting. which one did you buy?

i was hoping that i wouldn't have to match the power draw of my computer (which will be in the 550-600w range probably) with that of my apc ups. are you essentially saying that this is the case though? :(

if that is indeed the case, what about this apc ups?
Brand APC
Model BR900
Input Voltage Range 120V
Input Frequency 47-63 Hz
VA Rating 900 VA
Watts 540 Watts
Output Voltage 120V
Outlets 7
Battery Run Time Typical Backup Time at Half Load : 17.6 minutes (270 Watts)
Typical Backup Time at Full Load : 5.3 minutes (540 Watts)
Battery Recharge Time <8 Hours
Interface Port USB
Surge Protection
Data Line Protection RJ-11 Modem/Fax/DSL & RJ45 Ethernet protection
Surge Energy Rating 320 Joules
Physical Spec
Weight 22.50 lbs
Dimensions 12" x 9" x 17"
Package Contents BR900 UPS
RJ11 Cable
Driver Disk
RJ45 To USB Cable
RJ45 Cable
RJ11 Cable


May 26, 2004
Annoyingly, I live in an area that seems to have a power outage about every 3 months. This is weird to me because I live in a highly populated area in possibly the most electricity abundant area of the world (Quebec). Anyway, I got myself a meager 350 Watt UPS to run my monitor (19" LCD), Tower (PD820, Single HDD, NV6600) and my modem, router, and phone. I don't even get 2 minutes to shut down my computer when the lights go out! Still, I generally can manage to save my work and shut down. There's also a USB plug that automatically saves everything and shuts my computer down for me.

However, after such a power outage, the UPS charge is completely spent.

Conversely, it is convenient to run my modem, VoIP router, and phone off the UPS with the computer off, as it gives me more running hours that I've ever used for these. It's good to be able to call the paramedics when the power's out.

Anyway, my little story should tell you that my computer (~200-250 Watts) drains my 350 Watt, 500 VA UPS rather quickly. It sounds like your setup would either drain you UPS in seconds or trip the protective circuits.


Dec 8, 2006
yikes---this is going get expensive...

i am looking around tom's site here and i cannot find any articles explaining how to choose a backup ups. anyone got a link?

surely there must somewhere be a reliable article about how to go about matching a backup ups with your systems power usage/wattage


Dec 8, 2006
there's also this refurbished apc for $100:

Model Number: BP1000
Wattage: 670 Watts
Voltage: 120 Volts
Wave Form: Sine Wave
Number of Outlets: Six standard 15 amp 120 volt plugs
Dimensions: 9" x 7" x 17"
Other Features: Automatic Voltage Regulation (AVR), Basic Serial Communication Port, Surge Protection Port (for network or phone cable)

this one must have enough wattage, since it nearly matches my 700w psu
i am assuming wattage is what i need to be judging it by?

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