What size UPS do i need? (300VA isnt cutting it)

[JEDI]

I have a Conext 300VA UPS.

this is whats plugged into the backup side of the ups:
desktop -> AMD quadcore phenom II 960T 3ghz, Radeon 4850, 1TB hard drive, 1 dvd burner. ==> used to surf web.
monitor -> 27" Dell LCD (2500 x 1440)
DSL modem -> Westell (default Verizon DSL modem)

had it for a year and never went to battery backup till today when power went out for a few min due to storm.

my desktop instantly went down. battery back up did not kick in. UPs beeped. after the desktop turned off, DSL modem came back on as if someone turned power off/on.

so apparently a 300VA ups wont cut it.
How do I calculate what will?

And what do you estimate what I need w/o going overboard??
(yeah, I can get a SmartUPS 1500 for $300 but that's overkill, not to mention expensive.)

 

[sm625]

Rather than replacing the UPS, which could cost over $100 for a model that will reliably output the 400+ VA that you need for that rig, might I suggest simply upgrading the rig to something that WILL work under that UPS? A haswell i3 would outperform that 960T and use 1/3 the power at the wall. Also, an R7-250 would outperform that 4850 and again use 1/3 the power at the wall, perhaps even less given the vastly improved idle power. You might not even need an external gpu. At any rate you can easily build a system that can surf the web while pulling only 60 watts from the wall under moderate/heavy web surfing load.

 

[VirtualLarry]

LOL at thinking a 300VA UPS would be enough for a desktop PC. Those are like 120-160W.

I go for the 1200VA UPSes, which are like 700-800W. Yes, they do cost more.

OP, stop trying to cheap out.

 

[Torn Mind]

The monitor and whole computer probably pulls down 240 watts AC power at idle(40 for graphics card, 120 for rest of the computer, 80 for monitor. Load it up, and the UPS will simply not be able to provide power when it cuts off.

When sizing PSUs, DC wattage matters. For UPSes, AC or "at the wall" power is what matters. You probably should get a 500 watt unit; the VA will be greater than the wattage ratings.

 

[Blain]

OP, stop trying to cheap out.

2nd

$135 shipped is way less than $300.

 

[JEDI]

2nd

$135 shipped is way less than $300.

I was talking about one of these (SmartUPS):
http://www.amazon.com/APC-SMC1500-Sm...words=smartups

 

[VirtualLarry]

But why do you need to go from under-provisioned (300VA) to sheer overkill (SmartUPS)? There are models in-between, such as the one Blain suggested.