[Asterisk-Users] UPS rating for SOHO asterisk box

[Colin Anderson]

>I have a PIII-800 box with two X100P and one TDM400P plus graphics
>adapter, an IDE hard drive etc. Will a small 400VA box be enough for
>this?

It's tricky sizing UPS'es to be bang on the money. The rule-of-thumb
calculation for VA is watts/.6 . So, for a 200 watt power supply / .6 is 333
VA. Tricky part is, a 200 watt PSU is max power, which your PC will not draw
all the time. You want to be bang on the money, so you have to determine the
watts of every individual component like this:

(numbers out of my ass)

HDD 		35W
Mobo & CPU	80W
Video		10W
NIC		5W
TDM400	20W
----------------
TOTAL		160W = 266 VA

In my experience, oversizing your UPS gives you a comfortable margin, and
these days, pricing between, say, a 400 to 600 VA is minor, and you get
added runtime as a bonus. But if you want a decent runtime on your box, and
it's of the 200W PSU variety, the 400VA will probably be OK given what you
have stated. 

hth