UPS

[dodonga]

So while looking into buying my new comp, ive decided to go with a 750 watt corsair PSU, i wanna get a UPS to protect the computer from the ocassional power shortages that may occur from time to time. Do i need to get a power supply with atleast 750 watts? or will a 300 or 400 watt one do?

 

[mindless728]

depends what components you are using

system specs please

 

[dodonga]

well ill probably be using a setup something along these lines:
4gb dd3 1600
WD Caviar Black 1TB x2
Phenom II X4 965
Ati Radeon HD 4890 (might add another one later)
CM Haf 922

 

[dodonga]

I forgot to mention ill also be plugging in a 23" lcd i guess that uses up considerable power as well

 

[endorphines]

one thing to keep in mind is that while VxA=W a 1000 VA UPS will supply considerably less than 1000W... a good rule of thumb is multiply the VA rating by .7. so in the 1000VA case you'd be looking at 700w that it can supply. if you figure you won't top 500W with your machine and a 23" LCD added in a 1000VA one should be good. Again that's just a rule of thumb, if you can find the ratings provided by the manufacturer ratings soemtimes they provide both VA and W ratings.

 

[DeW itt right]

Head over to eXtreme Outer Vision, their PSU calculator sizes your system's PSU (free version) and UPS (pro version, $10 lifetime)...

 

[dodonga]

Well my original question is still not answered, im just asking if theoretically speaking a computer is using say 750 watts for its normal load, and you have a 500 watt UPS, will the UPS provide the PSU with enough power when its plugged into the wall, and second can it keep it on once the lights go out and is using its stored power to keep the computer on?

 

[DeW itt right]

From my understanding, your UPS wattage doesn't exactly have to be the same or higher wattage as your PSU but it obviously has to be able to handle your actual usage. For example, you have a 750W PSU but your peak usage load may only be around 400W so you'd only need a 400W+ UPS. I'd recommend getting a Kill-a-Watt and seeing what your actual peak usage is but keep in mind you may upgrade your PC more often than your UPS so leave room for expansion. I'm also not aware of typical UPS efficiencies but keep in mind a 400W UPS may actually max out at 350W because no PSU or UPS is 100% efficient.

Just looking at THIS UPS at newegg for examples sake, it tells you it's rated for 600W and can handle the following:

Entry-level PC with 19" LCD (150W) - 15 min.
Midrange PC with 19" LCD (300W) - 7 min.
Performance PC with 19" LCD (500W) - 3 min.

Keep in mind though that you'd only be using upwards of 500W if you continued heavy work or gaming while the power was out. The Kill-a-Watt would give you a much more realistic understanding of how little of that 750W PSU is actually being used during light-to-moderate usage.

From my understanding, when the power is on the wall outlet is filling the UPS battery at the same time the PC's PSU is drawing from the battery. They run this way to avoid any lapse in power when the house power goes out. So to answer your other question, no. A 300W or 400W UPS can't supply 600W when plugged into the wall (nor would you want it to because if the power did go out at that elevated wattage your UPS would be pointless).

 

[dodonga]

Ah interesting ill look into the kill-a-watt to see the actual usage once i get the pc