UPS Question

[Ermz]

Hey guys,

I'm running an APC UPS that's rated to 980W. Now, does that prohibit me from hooking up a PC to it with a 1kW power supply (along with my Dell 24" monitor)? Bear in mind I don't intend to run anywhere near 1kW of draw with the PC, but I don't know how spikes can work, and whether the power supply would be able to damage the UPS or whatever.

This is the UPS model: http://www.apc.com/resource/include/techspec_index.cfm?base_sku=sua1500i

Thanks in advance!

 

[TheWinterSnow]

Well it depends on how much power your PC actually draws. Your PSU is 1kW which means it can handle a load of up to 1kW, that doesn't mean the hardware in your PC is pulling 1kW. You have to find out how much power each component in your PC draws at full power. Unless you are running two very large graphics cards which tend to pull 400W a piece, most likely your whole system may pull 400-500W if you have an absolute monster for a PC which is almost unheard of.

 

[jipchen]

Wow, why would you need a 1k power supply?

I read the UPS should be rated a bit higher than the (maximum) power supply of your PC because of the spikes you mentioned. So 980 and 1k probably isn't ideal..
You can use the APC sizing selector to get an idea what they think is ok: http://www.apc.com/tools/ups_selector/index.cfm
(I used your rough specs and it said the 1500VA unit would suffice)

@TheWinterSnow: The average power consumption is not the problem of course, but the system startup spikes could be.

 

[dani]

ermz, the 1kw is the rated max of a power supply, and chances are unless it's really expensive it might not even be able to sustain it for very long

in all honesty though, my mac pro PSU is rated at 1kw, but no matter how hard i push it, i've not seen it pass 400W usage.

if you want to get a rough idea, take the rated max of all your components:
- the max TDP for your CPU,
- the max current draw of the graphics cards, and if you can't find that, the (absolute) max is 75 + 150 * number of aux power cables it has going into it
- add 20 watts for every magnetic hard drive and DVD drive you have (ie, not SSDs)

take this number, multiply it by 1.5 (to account for PSU inefficiencies) add 100 watts for your screen (or 150 if it's 24"), and that is a worst case power draw for your computer.

bear in mind, this is an over-estimation of how much power your computer will use when it is doing all of the following at once:

the CPU is being maxed out, the graphics cards are being maxed out, the hard drives are being powered on, and you're burning DVDs in all your DVD drives.

your UPS should be fine.

thanks,

 

[TheWinterSnow]

The average power consumption is not the problem of course, but the system startup spikes could be.

The spikes aren't any more intense than when gaming. In a computer it is the CPU that uses full power during startup. If you have a 140w CPU then you are running 140W plus whatever else is drawing power. The power cannot spike beyond 1kW or else the PSU is going to have a problem and like I said before, unless he has an absolute monster for a PC, I cannot see a non-gaming PC spike anymore than 500w. Hell on my setup, I have a 3.0Dual core, 4gigs DDR3 2 HDD 1 external drive, a 24in monitor, Bx8a (130w total) and a PS3 all connected to my battery backup and still doesn't spike 300w when my PC is on startup.

The only reason PSUs come in 600+ watt flavors are for the gamers because the large graphics cards can idle at 200w a piece and peak 400w, that is 800W total just for two cards not counting the rest of the PC. The rest of the computer takes almost no power even during startup compared to that.

With that in mind, even if he does have a 1kW PSU, even if his entire rig spikes 500w, a 980w UPS is sufficient.

 

[Ermz]

Thanks guys. I know teh PC itself will likely never get close to 1kW, but I wanted to make sure there wouldn't be any spikes in how much it draws that could throw the PSU out.

And yes I'm getting a 1kW power supply because I plan to either Crossfire a pair of 6970s or SLI 570s!

 

[TheWinterSnow]

Thanks guys. I know teh PC itself will likely never get close to 1kW, but I wanted to make sure there wouldn't be any spikes in how much it draws that could throw the PSU out.

And yes I'm getting a 1kW power supply because I plan to either Crossfire a pair of 6970s or SLI 570s!

If you plan on getting 6970 crossfire or 570 SLI then you will need to pickup at least a 1500VA UPS. The 6970s pull 430w max a piece.

 

[kev]

Ah, upgrading the gaming beast! Slightly off topic dude, but you have you seen the 6990 is out extremely soon? Not sure how it will shape up against the two 6970s though yet.
back to the power, does the UPS deliver clean quiet power in your studio? I've really struggled a lot with ac hum/interference lately and was wondering if it gets around it all?

 

[soundsunderground]

Is there some reason you are prohibited from looking at the load meter on that UPS? They put those there for a reason.

 

[Ermz]

If you plan on getting 6970 crossfire or 570 SLI then you will need to pickup at least a 1500VA UPS. The 6970s pull 430w max a piece.

Sure, 1500VA is exactly what my current UPS is.

I ran the guide on their site, and they recommended the 1500VA as being functional for me - even if at max load it would be at 80% capacity!

Live on the edge and all

@Kev: I've seen the reviews on the 6990. Hot, noisy, power-hungry! Not for me. As always, two single cards in Xfire or SLI perform better than these dual-card-in-single-body configurations. The Nvidia 590 is coming out soon though... should be the same story. I think two 580s or 570s back to back.