which size ups get?

[Guest]

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

I'm having a little trouble determining what kind of UPS to get. I need to
to power two computers (no monitor support is necessay).
comp1 has 2 sata drives and runs an athlon2000+ and a ti4200 videocard.
comp2 has 6 ide drives, 1 dvd, athlon64 3000, 5900xt videocard, tvtuner

both have 400w powersupplies. I'm checking out pricewatch but all I see is
350va,500va,750 or 1000va units, not sure which one will work without
wasting money

 

[Guest]

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

ChangeGuy wrote:

> I'm having a little trouble determining what kind of UPS to
> get. I need to to power two computers (no monitor support is
> necessay).

> comp1 has 2 sata drives and runs an athlon2000+ and a ti4200 videocard.

> comp2 has 6 ide drives, 1 dvd, athlon64 3000, 5900xt videocard, tvtuner
>
> both have 400w powersupplies. I'm checking out pricewatch but all I see is
> 350va,500va,750 or 1000va units, not sure which one will work without
> wasting money

VA = volts x amps, but PC supplies are capacitive and therefore the VA
has to be higher than the watts going into the supply, which is roughly
30-40% higher than the power going out.

The websites for APC/Conexant, TrippLite, and other UPS makers should
have estimators, and the information is also printed on the product
boxes. I believe you'll be able to get by with a 500 VA unit because
few computers draw anything close to the maximum ratings of their power
supplies.

A very conservative estimate of the power can be obtained from the
spreadsheet at http://takaman.jp. The VA rating of the UPS should be
roughly 200% that estimate, 120-150% if your power supplies have active
PFC (power factor correction). Active PFC means no voltage selector
switch on the back of the supply.