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UPS Choice

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May 2, 2010 7:09:38 PM

Hey guys, can you please advise me as to how one chooses a UPS?

My power supply Seasonic S12 600W Silent ATX2.0 Power Supply ( i dont think they make these anymore). Does this mean i need a 600 wat UPS? All the ones i seem to find are at the range of 230 - 300.

Thanks.

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a b ) Power supply
May 2, 2010 10:40:48 PM

OK, the important thing to realise is that UPS watts ratings are meaningless, similar in this case to the ratings on the 600W psu.

The 600W rating is the peak power output, as well as the maximum rating...if you run a PSU rated at 600W at 600W constantly, it's not going to last so long.

In considereing a UPS, you want to look at Volt-Amps or VA rating rather than watts, so a 600W PSU at full load takes 4.8Amps at 125V, meaning that you need at least a 840 VA UPS for your computer, prefereably higher, especially if you plan to have other things on battery backup.
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May 3, 2010 12:11:41 AM

Whoa...the Volt-Amp rating really has nothing to do with the power supply - at least not in the way you're thinking. I've got 6 UPSs in the house, most hand-me-downs powering the kids' PCs and the home theater PC. I just recently bought a new APC 1500Va for $165 at Best Buy. I upgraded from a 650KVa. I have a 700W Active PFC PSU. The 750Va/310W would hold my system for about 6-7 minutes, while the 1500Va will hold it for 25-30ish. That's why I upgraded - because I needed more time. Previous to the 750Va I had a 500Va/240W (on my old C2Q build), but it would only hold it for about 4 minutes.

The Va rating is really more for measuring how long the UPS can hold a given system based on the wattage it draws. For example, my rig draws 230W at idle and about 350W at load. That's an overclocked 920, 12Gb memory, 160Gb SSD, a 1Tb WD Black and a 1.5Tb WD green, and a 5870 with an overclock. Oh, AND 3 24" 1080P monitors. 350W MAX with my 700W PSU. You may have a 600W PSU but it's HIGHLY unlikely, unless you're running dual GTX480s, that you're actually drawing 600W and it's probably less than half that. Without knowing your rig, you could compare yours to mine and kind of make an estimate as to your draw.

The APC BX1500G (the one I have) is 1500VA/865W. You probably don't need one that big, but it really depends more on how long you want your PC to stay up. I wanted close to 30 minutes and I got it on sale for $165 (it's now $199 - ouch). If you just need good surge protection with 5-8 minutes, you could go with a 600va model from whomever you choose. Want 10-12, go with 800va. Again, this depends on your PC so let us know your build (processor, memory, hard drive, etc...) and I can give you a rough estimate based on how long you want it to stay up in regards to how many VA you need.

The only thing you may want to watch in regards to wattage is to make sure it's got enough wattage to power what you need. A UPS with only 200W wouldn't do squat for my rig and would drain the battery in under 2 minutes, while a the 750VA/310W that I had worked just fine. As far as not finding ones with higher wattage, as the VA increases so does the wattage it can handle, so I suspect you're not looking in the right places.
a b ) Power supply
May 3, 2010 12:27:34 AM

Yes, well I was calculating just given the information given, I was drawing the assumption that he was using all 600W. Besides that remember that VoltAmps is just that, Volts*Amps.

Also, like I mentioned before watts are pretty meaningless as the poster above mentioned because computers are non-resistive, so the amount of power they draw is quite variable. The other thing to consider is the power facter. A typical PF (power factor: Watts / VA) forcomputers may be as low as 0.6, which means that if you record a drain of 100 Watts, you need a UPS with a VA rating of 167, although I would say that aim for atleast a PF of .7.

On a final note, aim for a QUALITY manufacture, like APC, TrippLite, or Opti-UPS.
May 3, 2010 9:17:23 AM

The reason i posted here is because i had a cheap 600Va model (didnt even have a brand), that simply turned off when the power went out. I kind of assumed it wasent strong enaugh to power my pc.

Here are the specs:

Western Digital Caviar Black 500GB SATA-II 32MB Cache - OEM (WD5001AALS)
Raptor X Hard Drive
Asus Crosshair III Formula AMD 790FX (Socket AM3) PCI-Express DDR3 Motherboard
AMD Phenom II X4 Quad Core 810 2.60GHz (Socket AM3) - Retail overclocked to 2.86 Ghz
Corsair XMS3 DHX 4GB (2x2GB) DDR3 1600C9DHX Twin3X (TW3X4G1600C9DHX)
BFG GeForce GTX 260 OC2 896MB GDDR3 PCI-Express Graphics Card

... i think thats all of it.

And btw, my computer draws about 200 W on idle.

Thanks for the input!
a b ) Power supply
May 3, 2010 11:20:36 AM

thegatekeeper said:
The reason i posted here is because i had a cheap 600Va model (didnt even have a brand), that simply turned off when the power went out. I kind of assumed it wasent strong enaugh to power my pc.

Here are the specs:

Western Digital Caviar Black 500GB SATA-II 32MB Cache - OEM (WD5001AALS)
Raptor X Hard Drive
Asus Crosshair III Formula AMD 790FX (Socket AM3) PCI-Express DDR3 Motherboard
AMD Phenom II X4 Quad Core 810 2.60GHz (Socket AM3) - Retail overclocked to 2.86 Ghz
Corsair XMS3 DHX 4GB (2x2GB) DDR3 1600C9DHX Twin3X (TW3X4G1600C9DHX)
BFG GeForce GTX 260 OC2 896MB GDDR3 PCI-Express Graphics Card

... i think thats all of it.

And btw, my computer draws about 200 W on idle.

Thanks for the input!


I would definately invest in a quality UPS, one from a reputable brand. I stay away from the cheap ones because they're ratings are often wrong/inconsistent with what you get. For your system to have room for expansion get at least an 850VA UPS.
May 3, 2010 4:04:43 PM

Shipping a UPS is prohibitively expensive. They're HEAVY as heck and there's batteries involved and I'd have to imagine shipping overseas would be even more expensive. You'd probably add 50% to the cost just for shipping. I think the only time I've ever seen the brand-name Mustek was with an old scanner I had. I had no idea they made UPSs so I can't speak to the quality. But, if that's the only option you have for something local, then it's better than nothing. Seems expensive (what is that...about $120?) for a name brand I've ever heard of that only has 4 outlets. That said, 1,000VA should hold the system you have in your info for a good 20-25 minutes fairly easily.
a b ) Power supply
May 3, 2010 5:29:49 PM

dkapke said:
Shipping a UPS is prohibitively expensive. They're HEAVY as heck and there's batteries involved and I'd have to imagine shipping overseas would be even more expensive. You'd probably add 50% to the cost just for shipping. I think the only time I've ever seen the brand-name Mustek was with an old scanner I had. I had no idea they made UPSs so I can't speak to the quality. But, if that's the only option you have for something local, then it's better than nothing. Seems expensive (what is that...about $120?) for a name brand I've ever heard of that only has 4 outlets. That said, 1,000VA should hold the system you have in your info for a good 20-25 minutes fairly easily.


At the current exchange rate is closer to $140, but thats irrelevant. What is relevant is that I have never heard of the brand so I can't attest to it's reliability. As to brands you find, google the model number and review and see what people say about it. Since you are in Europe, there is little helpe people from the US can provide about UPS models as they are different, as are the voltages.
May 3, 2010 8:12:06 PM

Just a note on the UPS you did have (the 600Va model). It shut off more than likely because the battery was dead, not because it wasn't strong enough. I have a 450va powering an Athlon II X2 240 with 6Gb of memory. It holds it for about 4 minutes which is long enough to have the UPS power it down and protect it. I have had UPSs do what you describe - that's when it's time to throw them away unless the battery is replaceable (which is highly unlikely on the cheaper ones). APC made some for a while that had replaceable batteries, but it seems like they only lasted a year (maybe a little more) before they wouldn't do squat. Generally, the batteries should last a few years. Like all rechargable batteries, they will eventually die.
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