What type of UPS for Mac Pro?

Discussion in 'Mac Pro' started by c073186, Jan 20, 2008.

  1. c073186 macrumors 6502a

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    Nov 2, 2007
    #1
    Well I just placed my $5,000+ order for my new mac pro and now it is time to consider power protection. I am going to need to plug in my Mac Pro, LCD monitor, laser printer, speakers, and mouse (MX1000). Does anyone have any suggestions or recommendations as to how much protection I need for that? They have so many varieties with different voltages ... I have no idea what a Mac Pro requires. All I know is that after spending that kind of money I want to protect my investment with something of high quality.
     
  2. yesthisisapc macrumors member

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    #2
    I like to overcompensate for my shortcomings as a man by getting the 1500VA model.
     
  3. Soop53 macrumors regular

    Soop53

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    Ohio
    #3
    I have been using an old Kensington MasterPiece Plus for years. I hope this is still good. The low voltage sound/light still works on it as we do experience brown outs here on occasion.
     
  4. ErikAndre macrumors 6502a

    ErikAndre

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  5. deathshrub macrumors 6502

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    #5
    Ditto, that's what I went for as well.

    There's another thread around here somewhere that discussed what UPS would be appropriate for the Mac Pro, you won't have to look very hard to find it.
     
  6. Random Chaos macrumors member

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    Jan 16, 2008
    #6
    Looks like the old Mac Pros used a 980W PS. The new Mac Pro specs state 12A at 120V - that's about 1440VA peak. But unless you max out HDs, video cards, and keep the system running max on CPU constantly, you won't actually pull anywhere near that.

    I've got a 1000VA on order. I'd have gone higher, but I do have a budget. That will keep it up during a power flicker, and shouldn't have a problem for a short period time even with near full draw, which is all I really need an UPS for. I have an 1100VA for another computer; I could switch them, but the other doesn't have Mac software support.
     
  7. Blogger macrumors 6502

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    #7
    I had an APC smart UPS 750 which worked fine until the battery started to age. To check a UPS, put the computer to sleep, pull the plug from the wall and then wake it up. After a year, it would not do the job (Mac Pro only, all other ancillaries on a second unit). So replaced it with an APC Smart UPS 1500, which is probably slightly overkill for just the computer, but ideal if you want to connect the monitor, hubs, powered speakers etc..
     
  8. Random Chaos macrumors member

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    Jan 16, 2008
    #8
    I did a quick calculation last night. As I recall, the 2.8GHz CPUs run at 80W. The 3.2GHz CPUs run at 150W. That's 140W difference for two CPUs, so, since they come with a 980W PS, it should probably never draw more than 840W on a Mac Pro with 2.8's, so a slightly lower UPS would be fine. Approximate calc is 840*1.4 = 1176VA.
     
  9. Blogger macrumors 6502

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    #9
    I don't quite see the logic of this (not that it's not there, i just don't see it). After some thought, I understand the 140W difference (when added and then subtracted), but don't understand the next leap to the actual power supply size, or the assumption of the draw level. On top of that, I'd be interested in the 1.4 multiplier you then used, where does that come from? I assume it may be an electronic industry formula, but a slightly more expansive post would be appreciated.

    Having said that 1176VA is not an unbelievable figure. APC recommends a minimum of 1000VA for the mac Pro.
     
  10. amik macrumors regular

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    Dec 11, 2007
    #11
    Here is a link to the other thread: http://forums.macrumors.com/showthread.php?t=411989

    Random Chaos,

    Where are you pulling that 1.4 multiplier from? When I look at it, if you have 840 watts with an approximate power factor of .6 (probably a little conservative), you would need 1400 VA (840/.6).

    Blogger,

    I tried to post a decent explanation of the calculations involves in UPS sizing in the thread linked above (primarily the difference between VA and Watts). If I was not clear or I missed something, let me know and I'll try to explain it better. Here is the post: http://forums.macrumors.com/showpost.php?p=4728114&postcount=6

    Don't forget to add in the draw of your monitor and other items that need to stay running to allow you to shut the system down when sizing your UPS.
     
  11. elmo151 Guest

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    Jul 3, 2007
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    NYC
    #12
    Apc

    I have an APC unit. It works.

    Last summer there was a power failure in NYC. I was sitting at home working on my Mac when I heard a buzzer. It took a few seconds to realize it was the APC warning me of a power failure. I had plenty of time to shut the mac and peripherals down without any problems.

    Highly recommended
     
  12. Blogger macrumors 6502

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    #13
    Thanks amik. Would that have anything to do with back EMF?
     
  13. Random Chaos macrumors member

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    #14
    The general rule for calculating UPS requirements is:

    Sum of VA of components of the computer, where VA = V * A = approximately 1.4 * W.

    Using the A*V max of the actual PS, or using the Wattage max of the actual power supply, doesn't give you the real draw, only the max draw of the power supply. What you need is the real maximum draw of the equipment the power supply drives. Since we know that the max draw of a Mac Pro is 980W with it maxed out spec wise, and we know that max spec includes 2 150W draw processors, we can say that the actual draw of a 2.8GHz Mac Pro cannot draw more than 840W since they do not change the PS between 2.8GHz and 3.2GHz. Similarly, less on the PCI-E bus will require less draw.

    As for the 1.4 multiplier, I have found reference to it in multiple sources. For one reference, take a look here: http://www.wrecc.com/formulas.aspx

    The number changes based on the voltage being supplied as I recall, but I don't have time to sit down and calculate it out right now. The power factors I've seen run about 0.67 - 0.69 for 110-120V.

    Besides, if it really is 0.6, then you will get 980/.6 = 1633VA, but we know that 12A * 120V = 1400VA. Can't both be accurate.
     
  14. Blogger macrumors 6502

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    #15
    Ah, now I understand what you were saying. Thanks.
     
  15. mrbc19 macrumors member

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    Nov 13, 2007
    #16
    Definitely go with the Smart, or RS 1500 models. I went with an APC RS900, and found out that it was insufficient. While the RS900 can easily power the computer with monitor long enough to shut down while on battery power, it is waking from sleep while on battery power that will cause a problem. It is a well documented problem, you can see here: http://discussions.apple.com/thread.jspa?threadID=685213&tstart=0

    In that thread though, the original poster even had a 1500 VA unit, and it still overloaded when waking from sleep. So you might want to go even bigger. I think the smart ups 1500 worked well though.
     
  16. amik macrumors regular

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    Dec 11, 2007
    #17

    The supply voltage alone does not dictate the power factor. The load being driven determines the power factor. The formula is VA = W/PF. If you know, based on measurement, the maximum instantaneous current draw, and the supply voltage, you can calculate VA directly as you suggested. The relationship of VA (power delivered) to Watts (power consumed) is described by the power factor. Using a multiplier of 1.4 is just an assumption that the power factor is .71. Like I said in my post, I use .6 which is probably on the conservative side.

    Given that a computer is a variety of different resistive and reactive loads (processors vs. hard drives), the power factor will be determined by the sum of the current delivered instantaneously (during 1 phase) divided by the average power delivered over all phases over some period of time. Motors and other reactive devices momentarily deliver power back to the supply which causes their average consumption to appear lower than the instantaneous current delivered (electrical components need to be sized for the instantaneous current).

    All that being said, if you size your UPS to the specified VA of the power supply, plus any other critical equipment, you are going to be safe. Sizing for the VA of equipment downstream of the power supply is only appropriate if the power supply does not have active power factor correction.
     
  17. tvbi macrumors member

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    Jul 14, 2004
    #18
    I've been using the Ultra 2000VA for over a year without problem. It even switches to battery power when my sister power up her iron in her room :rolleyes:
     
  18. barijazz macrumors 6502

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    Dec 29, 2007
    #19
    Can't you check the voltage requirements of your computer by opening energy saver?
     
  19. Pressure macrumors 68040

    Pressure

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    #20
    The Thermal Design Power of 80 Watt is not the same as the peak power draw of the Quad-core 2.8Ghz.
     
  20. AviationFan macrumors 6502a

    AviationFan

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    #21
    That's the one I have on order, too. I hope it'll be good enough to power my new 2.8GHz MacPro along with a 30" ACD.

    - Martin
     
  21. Toups macrumors regular

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    Nov 23, 2007
    #22
    A nice alternative for those looking to save a few bucks is the Best Buy "Geek Squad" brand UPS which list for $30 less than the APC and are often on sale for and additional $20 off.
     
  22. faumble macrumors regular

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    Jan 8, 2008
    #24
    Will a 600VA be enough fro a single cpu 2.8 macpro with 4GB of ram, two video cards (ati 2600 + nvidia 8800) and 4 hard drives (320GB+1TB+1TB+500GB) ??
     
  23. Toups macrumors regular

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    Nov 23, 2007
    #25
    More than likely not. Take into account each harddrive at a minimum of 30 watts, video cards at 150-175 watts each, processor/motherboard at 100, optical drives at 35 watts, and you will probably want a monitor too I am assuming (50-200 watts)?

    At a minimum, you will need 800 or more (assuming 100% efficiency), I would recommend no less than 950/1000kva for that setup.
     

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