DIGIT-ARC read-only archive · snapshot: July 23, 2026

390watt UPS(APC) but 620watt power supply

10 posts · originally from https://geek.digit.in/community/threads/390watt-ups-apc-but-620watt-power-supply.65256/

H
Harvik780 Original post #1
Aug 11, 2007 at 10:27 AM
My brother has a 390watt UPS(APC) 650VA but a HX620W 620 watt power supply.Will it cause any problems.

Waiting for suggestions
Still waiting.I think people generally neglect such facts about mismatch of PSU wattage delivered at usage by pc and that by the UPS.
BBThumbHealer
Aug 11, 2007 at 11:53 AM
i think this shud cause prbs in case of power failures coz a 390 watt UPS won't be able to handle the 620 watt power..

my suggestion ...get the total power supply of the PC to a socket which is connected to the invertor :)
Choto Cheeta
Aug 11, 2007 at 11:55 AM
@Harvik780

Install PowerChute software then run a Self test while system is on Load :D

that will give u an idea whats the actualy power requirements !!!

:)
M
magnet #4
Aug 11, 2007 at 12:07 PM
620watts power supply doesnt mean it runs at its full power..check with the above software how much power your system uses.......if its below 500w than 650va will suffice.....but if its more than that..than upgrade your ups to 800va or 1kva
utsav
utsav #5
Aug 11, 2007 at 12:08 PM
how to know that how much power my proccy hdd and all the cabby components r using without any ups software
R
realdan #6
Aug 11, 2007 at 10:23 PM
dont forget the monitor
H
Aug 12, 2007 at 9:19 AM
magnet said:
620watts power supply doesnt mean it runs at its full power..check with the above software how much power your system uses.......if its below 500w than 650va will suffice.....but if its more than that..than upgrade your ups to 800va or 1kva
I have calculated the peak power consumption at 450 watts.So it should suffice!!

utsav said:
how to know that how much power my proccy hdd and all the cabby components r using without any ups software
U can use PSU calculator online.:)
*www.extreme.outervision.com/psucalculatorlite.jsp
utsav
utsav #8
Aug 12, 2007 at 12:58 PM
thanx harvik
blackpearl
Aug 12, 2007 at 3:38 PM
620W SMPS does not mean that it draws 620W of power. The PC will draw only the power that it requires. 620W is the max power that the SMPS can supply, but you won't hit that mark. I can assure you that. You can easily use a 1000W SMPS with a 390W (650VA) UPS without problems.

A typical PC draws only 200-300W of power, max.
Rollercoaster
Aug 13, 2007 at 1:03 PM
simple note - maximum of a system is equal to the lowest rated item.

Power plant (say 1000 Mega Watts) -> HT Power line (say 10 MW) -> Power transformer(say 100KVA) -> LT power line (say 100 Kva) -> power cable to home (usually 5Kva) -> power meter (usually 2kva) -> Room MCB (6amps) -> UPS (320 Watts) -> SMPS (720 Watts)

So, The maximum power transfer to the end point cannot exceed the maximum of any intermediate step.