UPS Wattage

Discussion in 'Mac Pro' started by allupons, Jan 4, 2011.

  1. allupons macrumors member

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    Mar 11, 2010
    #1
    I just spoke with an apple tech support guy that seemed pretty knowledgable about an issue I have with my 6 core mac pro. When my furnace kicks on and off I get a weird clicking noise in my speakers and he said that it was due to slight brown outs or dips in power, and it was audible because the capacitors in the mac pro power supply aren't overly large and thus dont compensate well for this. His recommendation was a simple APC low wattage UPS. He said it wasn't important that it matched the draw from the mac pro power supply since all it had to do was compensate for the slight drops in power that my apartment occasionally experiences when the furnace kicks on.

    I wanted to double check that math here before I run out and pick a low wattage UPS up. I am not all that concerned about being able to run the machine in the event of a power loss at all, and I mostly just want to filter for clean power going into the mac. Does this sound reasonable?
     
  2. johnnymg macrumors 65816

    johnnymg

    Joined:
    Nov 16, 2008
    #2
    You can get a UPS with 10+ minutes of run capacity for <$200. Why mouse around with something that "might" be good enough.

    There are a couple of LOOOOONG threads on UPS's here. APC and CyberPower are two of the more popular brands but there are others that are probably of similar value.

    If you want to go upscale look for a pure sine unit. The cheapest are in the ~$250 range: http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3094992&CatId=234
    There are other vendors with similar pricing.

    cheers
    JohnG
     
  3. nanofrog macrumors G4

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    May 6, 2008
    #3
    Given it's an active PFC, a pure sine wave unit is what's really needed. Granted, Cyberpower makes a stepped unit that's compatible with active PFC based PSU's, it's possible to get a pure sine wave for the same money in the refurbished market (example), and they're better units.

    BTW, I'm no fan of Cyberpower from what I've seen of their other consumer grade UPS's (includes Geek Squad units, as they're the ODM).
     
  4. allupons thread starter macrumors member

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    Mar 11, 2010
    #5
    Well, I went with a APC 1500 VA pure sinwave and the good news is the clicking noise from the furnace turning on and off went away. The downside is the clicking noise from my bathroom exhaust fan turning on and off is still there and clear as day every time you turn it off. Also, 1500 VA is apparently crazy overkill, as during full renders and intense gaming with the 6 core and ati 5870 I have yet to surpass 340 watts once, and at most times I am hovering around 150 watts. Seems like a 1000 VA would certainly provide plenty of overhead, but I don't really know what to do at this point as the UPS didnt mute out the static click noise from the bathroom exhaust fan being turned off/on. Any thoughts?
     
  5. nanofrog macrumors G4

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    May 6, 2008
    #6
    1500VA is not overkill. The batteries wear with time, and it will make sure you've sufficient time to shut it down in the event of a power outage.

    As per the noise you're talking about, move the UPS (and thusly the system) to a different circuit.
     
  6. johnnymg macrumors 65816

    johnnymg

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    Nov 16, 2008
    #7
    Are you saying the MP PS is clicking? If so, then there's something 'not-right' with your UPS. No way should a power glitch get through the UPS to the PS of the MP. Other than trying a different outlet I'd just return the APC.

    JohnG
     
  7. nanofrog macrumors G4

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    May 6, 2008
    #8
    Trying another circuit can diagnose if the UPS is bad or not, and it's easy to do. ;)

    BTW, there's a pair of relays in the MP's PSU, and that may be the source of the "clicking" sound, such as a brownout triggering the AC side (you'll hear this when you unplug and re-plug the power cord in the wall). The second is activated by the power switch.
     
  8. allupons thread starter macrumors member

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    Mar 11, 2010
    #9
    Thanks for the replys. To be clear, the clicking sound isnt coming from the PSU or UPS, but the speakers attached to the mac pro. If they are turned off, there is no pop when the exhaust fan turns on and off. It isnt the speakers themselves though as I have tried several and headphones and all exhibit the pop. My thoughts after more research is that something is up with the switch to the fan itself, or something is up with the likely very cheap motor powering the exhaust fan and that noise is making its way to the mac pro somehow. The only weird part is that gaming machines I have previously plugged into the exact same outlet didn't produce these noises, with the exact same speakers.
     
  9. johnnymg macrumors 65816

    johnnymg

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    Nov 16, 2008
    #10
    Thanks for that additional info.

    Regardless of the source, I'd still be concerned about the quality/robustness of that UPS. The UPS should prevent ANY AC line disturbance from "upsetting" HW plugged into it. The popping speaker (if only plugged into the MP) would indicate that the UPS isn't filtering the AC sufficiently.

    One last thing: Unplug the UPS from the wall and see if the speaker still pops when the fan turns ON/OFF. This will confirm that the pop is caused by a power line glitch getting "through" the UPS when it's plugged into the wall.

    JohnG
     
  10. nanofrog macrumors G4

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    May 6, 2008
    #11
    From what you describe:
    1. It's on the same circuit as the bathroom fan.
    2. You're hearing noise created by the startup current when you hit the bathroom fan switch through your speakers. The same thing happens with a 20W Halogen desk lamp I use (same circuit as the speakers, and it has a step down transformer to reduce the voltage to 12VAC - neither of these are plugged into the UPS I use - straight off of the wall).
    BTW, have you installed CCFL bulbs in that fan (presuming it's got a light in it as well, and that both the fan and light are controlled by the same switch)?

    I ask, as CCFL bulbs have a high startup current. Worst case, you have a bad wall switch.

    Moving the system to a different circuit will work, but it's not damaging your system. So don't panic.

    Not a bad idea, but I'm suspecting the speakers may not be plugged into the UPS at all (nor do they need to be, as it's not a critical part of the system).

    The smallest details do matter. ;)
     
  11. allupons, Jan 5, 2011
    Last edited: Jan 5, 2011

    allupons thread starter macrumors member

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    Mar 11, 2010
    #12
    So the plot thickens. I unplugged the UPS from the wall with just the Mac pro and speakers plugged into the UPS and it STILL popped. I couldn't believe that. Does that mean the Mac is somehow picking the noise up through the air?! I was stunned that didn't fix it.

    Also on a side note. Do UPS make electric hums on battery generally? Mine is fairly noisy on battery.

    *Edit. Turns out the humming electricy noise is coming from the mac pro PSU when the APC switches over to battery backup. It is a noise that makes me fairly nervous.
     
  12. johnnymg macrumors 65816

    johnnymg

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    Nov 16, 2008
    #13
    Hah............ that does certainly mean the MP is getting tweaked by some RFI from that fan going ON/OFF. Try reorienting the MP and if that doesn't fix it try swinging a chicken over your head. Make sure you swing it counter clock-wise. Clockwise always seems to make problems worse for me. :eek:

    The PSU buzz is a known issue with square wave UPS's. That's why many people recommend pure sine wave UPS's.

    JohnG
     
  13. nanofrog macrumors G4

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    May 6, 2008
    #14
    I'm with jonnymg; try relocating the system (can reduce/eliminate reception of RFI/EMI).

    As per the UPS, what model do you have?
    If it's a stepped unit, you should swap it out for a pure sine wave unit as stepped types don't work with Active PFC based PSU's, which the MP uses (they can even damage the PSU, so don't discount this).

    Nice. :D
     
  14. 20eman, Jan 6, 2011
    Last edited: Jan 6, 2011

    20eman macrumors member

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    Mar 10, 2009
    #15
    Actually, I think that the fan switch noise is more likely going through the ground than through the air. Even if you unplug the UPS from the wall, if your mac or your speaker system has any connection to ground (through USB to a peripheral, or through DVI to a monitor, or just a conductive surface that is touching some part of your system etc.) then you could be hearing noise that the fan motor is injecting into your ground wires.

    I recently suffered a similar issue, where my APC SmartUPS 1000 would produce an intermittent grasshopper-like chattering noise that made its way into all my audio equipment plugged into it. I ended up bypassing the problem by using the mac's optical audio connection instead of an electrical audio cable, so the sound system was electrically isolated from the mac.
     
  15. allupons thread starter macrumors member

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    Mar 11, 2010
    #16
    Interesting. I will try raising the mac and such off of the ground and see if that cures the issue. Thanks for the suggestion.

    Turns out the UPS is not a pure sinewave, so I suppose that will be going back if it is actually potentially harmful.
     
  16. nanofrog macrumors G4

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    May 6, 2008
    #17
    I've presumed there's nothing else connected to the system that's still attached to the wall AC, even with the UPS plug was pulled (printer, speakers, router, ISP modem, .... = isolated from earth ground). If you're not sure if the case is grounding or not (floor), then place some rubber pads under it. ;)

    If the system's truly isolated from earth ground (nothing plugged into the wall - directly or indirectly), then it's RFI/EMI (no wire for AC/ground noise to enter the system). Signal grounds act as an antenna, especially those external to the system (SATA, USB, FW, .... can all pick up noise and introduce it to the system - they do contain shielding to reduce this effect, but it's not always 100% effective).

    BTW, the audio circuits in computers aren't that good, especially for noise rejection (computers are a very noisy environment). Optical signals do isolate this issue (between devices), as there's no wire to make a connection and transfer any of that noise. But RFI/EFI can still get in on the system side (i.e case may not provide sufficient shielding - not uncommon for this to occur).
     
  17. allupons thread starter macrumors member

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    Mar 11, 2010
    #18
    The mac pro had every single cable removed except for the power cable and speaker out cable when I did the battery test using the UPS, and the speakers were also plugged in through the UPS. Therefore, it couldn't have come through the power lines / outlets at that point. I do have carpeting in pretty much the entire apartment though, so when I get home I will be sure to test the rubber mat solution and see if that isolates the mac pro from whatever is popping. I would love to use the optical output instead in general, but I dont have any external audio processors in my computer room. All of that is in the home theater room with my receiver, and I don't particularly want to buy an external audio solution as the sound quality is completely fine with me so long as I can kill the pops from the exhaust fan.
     
  18. cutterman macrumors regular

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    Apr 27, 2010
    #19
    You could try a shielded audio cable on the chance that it is RFI affecting the line-in to your speaker amp.
     
  19. johnnymg macrumors 65816

    johnnymg

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    Nov 16, 2008
    #20
    What do you mean by "the speakers were also plugged in through the UPS"?

    I've never heard of speakers going through a UPS. ??? That might be an "issue" if the UPS is somehow disturbing the signal on those wires. Me thinks this is something you should change as a test.

    What you described sounds like a problem with RFI/EMI pickup on the speaker wires themselves. Also, carpet is a fine isolator unless it's wet/damp/really-dirty.

    Besides the issue with the speaker wires going through the UPS (???) the next thing you should try (after the chicken swing) is to twist the speaker wires. Twist the wires so that there is ~1 turn per inch. Twisted wires will help minimize noise pickup. If that doesn't work you may have to shield the speaker wires.

    Also, that fan might be getting ready to burn your place down. ??? :(

    What type of output on the MP is driving the speakers?

    Cheers
    JohnG
     
  20. 20eman macrumors member

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    Mar 10, 2009
    #21
    johnnymg, I suspect allupons means that the speaker amplifer was powered through the UPS.
     
  21. nanofrog macrumors G4

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    May 6, 2008
    #22
    To test this (totally isolate the earth ground), you only plug the computer, monitor, and computer speakers to the UPS (make sure you use the protected outlets, as some models have pass through outlets = wall AC, usually with some surge suppression). Then flip the bathroom fan on and off, and see what happens.

    Then put the computer speakers on the wall, and try the fan again (UPS's are noisy devices as well, and that may be getting through the speakers input wire).

    For normal use however, get the speakers off of the UPS, as it's an uneccesary drain on the batteries (computer, monitor, router, ISP modem only - critical components only). Printers, computer speakers, ... place on the surge protected outlets only, to a separate surge suppressor, or even directly to the wall (good idea to use a surge suppressor for all your computer's components, but not needed to function). Just keep the non-critical gear off of the inverter (extends battery powered run time so you can safely shut the system down).

    As mentioned, you don't need to use rubber mats under the computer with carpet.

    You still haven't answered a couple of important questions though;
    • Are there CCFL bulbs on the same switch as the vent fan in the bathroom (the startup current for these bulbs is high, and can cause arcing in the switch)?
    • Is the computer on the same circuit as the bathroom fan (relevant when everything's plugged back the way it shoud be)?

    You may be able to try a couple of tricks mentioned in the last few posts, but if they don't work or aren't possible, and you can't live with the noise, then you're going to have to spend some money to isolate the audio output to the speakers (go optical).
    I've the impression the speakers are self powered computer speakers (simple, inexpensive units <i.e. 2.1 configuration> with a 3.5mm mini-jack input that gets power off of a wall wort), and the mini jack input wire is soldered to the amplifier board inside one of the units.

    If this is not the case, we need the details (brand, P/N, input method, and where is it getting power).
    It definitely seems to be RFI/EMI (assuming the system was truly isolated from earth ground), and I'm not sure of the computer speaker's connections either. These small details are important (directed at the OP).
     
  22. allupons thread starter macrumors member

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    Mar 11, 2010
    #23
    Sorry about not posting last night, was too busy to even mess with the mac pro.

    To try and answer some questions though, the speakers are self powered logitecs in a 2.1 configuration with a subwoofer that powers the 2 satellites. They were plugged into the UPS with their power cable in the protected outlet as to completely isolate them from the wall outlet. Their audio was fed in from the mac pro's audio out 3.5mm jack, but the exact same behavior is exhibited if plugged in from the front headphone jack, so it isnt jack specific.

    It should also be noted that I can completely reproduce these results with my sennheiser hd 650 headphones which are powered through the 3.5mm jack directly on the mac pro (ie, i completely remove the speakers from the mac pro for this test). Their audio cable IS heavily shielded, so I really don't think audio cable shielding has anything to do with it. Also, the previous windows machine that was used prior to the mac pro with the exact same speakers didnt exhibit the popping noise from the bathroom fan, so I don't think it is any specific component or lack of shielding to be found in the speakers, speaker audio cables, or headphone cables as if it was it should have popped prior to the mac pro as well.

    I still have yet to try removing the mac pro from the carpet and onto a table to see if that affects anything while also running on battery, but this interference is certainly pertaining directly to the mac pro and not the speakers as it is the ONLY new piece of the puzzle. Also, this issue has nothing to do with the wiring/outlets as far as I can tell as the popping sound happens even when the mac pro has nothing attached other than the speakers or headphones and only is running off of a battery source having NO connection to the wall. The mac pro is running on the same circuit as the bathroom fan, but considering for these tests the mac pro is running off of the UPS battery which is not even plugged into the wall, i no longer think the power cable / outlet has anything to do with the popping noise.

    Hopefully that answers some questions, and I will be sure to lift the mac pro onto a table and run the test again to see if it cures any issues.

    *edit There are no CCFL bulbs attached to the fan switch. It is ONLY the fan that turns on and off with the switch.
     
  23. johnnymg macrumors 65816

    johnnymg

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    Nov 16, 2008
    #24
    Thanks for that additional info.

    Just to be sure: You're still get this popping sound from the headphones when the UPS is unplugged from the wall AC and NO other ground/outlet is connected to any of the peripheral MP HW? If so, then I'll stick with the theory that EMI is somehow upsetting the audio output of the MP. That must either be a crap audio driver or that fan ON/OFF is producing huge RFI/EMI pulses.

    JohnG
     
  24. philipma1957 macrumors 603

    philipma1957

    Joined:
    Apr 13, 2010
    Location:
    Howell, New Jersey
    #25
    Lets talk about your bathroom fan. Make and model please.

    I have installed around 30 bathroom fans and some have motors that need caps to start. They shoot a lot of juice right when you turn the fan on to fire up the motor those caps can be double the voltage for a spilt second to start the fan's motor. If you have an aging cap inside this can be the cause of the sound. If the ground wire is loose on the fan this can be why. How old is the fan 3 or more years of heavy use can be enough to kill the cap.
     

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