Mac Pro Mid 2010 random powers off, can't always turn back on

Discussion in 'Mac Pro' started by RobertSix, Jan 23, 2015.

  1. RobertSix macrumors member

    Sep 21, 2012
    Hi everyone, I've come here as a bit of a last resort after hitting some serious issues with my MP.

    Mid 2010
    2 x 2.4ghz quad intel
    24gb 1066mhz ram from crucial
    240gb mercury PCIe ssd
    3 x HDD's (1tb WD, 2 x 2tb SG)
    ATI 5770 stock gfx

    Basically as the title says, I'm having power issues, and Apple repair have been unable to help with properly, although they've tried.

    Apple put in a new power supply, and from their end it appeared to be working. On getting the MP back it seemed ok for a few hours, then just turned off. As though somebody just pulled the power chord out. I went to turn the machine on again and the button was unresponsive.

    I did a SMC reset and the typical things Apple suggest. Checking power chords etc. Maybe an hour later I tried turning the MP on again and it booted.

    I thought maybe its a software issue, so I booted into windows bootcamp. It got about halfway into boot, and then, simply turned off.

    So I sent it to Apple again, and they ran extensive tests for a week. No problems found, and they sent it back.

    Now, I get the machine back and boot into OSx no problems and just leave it idle. 5 hours or so later - it's suddenly off.

    I think perhaps it could be a hdd fault, bad sectors or whatever, so I take out all the hdd's, leaving just the PCIe SSD drive in, and stock 5770 gfx card. But the problem still persists. I ran disk utilities and techtools (all tests) on the SSD and no bad sectors, and all ram checks etc etc - no problems found.

    I got off the phone about an hour ago to Apple Care, and they said that it sounds like it is a problem with my power - that I should take the MP to another place and see if the problem exists there. But I'm not sure that makes sense, if there was a brownout in the power and the MP turned off due to not having enough power, surely I would be able to turn the MP on again?

    Is there something I don't know about how the MP responds to a brownout - does it have some sort of check it does when you push the button again or a timer or something like this? I don't think so.

    I've been searching around to see if anyone else has had similar problems and I haven't come across any - has anybody here had this sort of issue? How can I diagnose it?

    Just today I've done a clean wipe of the boot drive and put on 10.10.1. And that's it. I got about 80% through the install and the MP turned off. Rebooted and installed again. I've been running diagnostics since and can't find anything.

    Any ideas?

  2. MacSince1985 macrumors 6502

    Oct 18, 2009
    Half way through reading your description, I was also suggesting a power issue. Do you have a UPS? If not, I recommend getting one. Even if that's not the problem, it will protect your Mac. Most models also display incoming voltage and will beep if you're over or under a normal range.
  3. RobertSix thread starter macrumors member

    Sep 21, 2012
    Thanks 1985. I'm sure it is possible - would love to know for certain. How can one even test this sort of thing? I've got a fluke multimeter with min/max peak testing for A/C - I was trying to learn about testing for power quality by comparing RMS to the peak - am I kidding myself?

    I'm definitely not ruling it out and I've been browsing for UPS since it all started. Thinking APC's SMT1500I. So when there's a brownout typically they make some sort of sound or notification? This would be great to know. I really should have got one sooner.
  4. ScottishCaptain macrumors 6502a

    Oct 4, 2008
    That depends.

    The physical unit itself will make a click and a loud bonging noise as the transformer comes online on the inside. There's a good chance one or two fans will spin up as well to keep the regulators cool. This will occur when the unit senses a low or high power situation (brownout/overvoltage) or when you experience a complete loss of power. The fans will usually run for 1-2 minutes after such an event occurs before they shut off.

    I don't have any experience with the SMT1500I (looks like a great unit though), but my SUA1500 (the older Smart-UPS model) will beep when the power goes out, but not during an under/overvoltage (it just makes all that mechanical racket mentioned above).

    If you want software notifications, that's up to the software. Under OS X, you basically get "free" UPS monitoring and automatic shutdown via the Energy Saver preferences panel, but that won't do anything other then turning your computer off in the event of a power loss. I'd assume you'd need some sort of UPS package to actually sit there and monitor the UPS status then record what happens when it happens if you want a log of all the power events.

  5. TruckdriverSean macrumors 6502a

    Feb 28, 2009
    Texas, US
    I'll tread carefully here as my understanding of power issues is very limited.

    Basically it was explained to me that computer PSUs are quite sensitive to power quality and will just reject the power if it is outside narrow parameters. So shutting off is normal if the power quality isn't up to par.

    The easiest/cheapest way to test is to move the computer to a different location. First I'd move it to a different part of the building, on a different breaker. If there's something on that first circuit that is amiss, it will work in new location.

    If that doesn't work, you might try a new location altogether, as in a friends house, assuming they don't live right next door. Of course, moving a cMP is a real PITA, so you could always just get a ups and keep the receipt.

    Just to reiterate, I'm far from knowledgable on this subject, but that is my understanding.
  6. RobertSix thread starter macrumors member

    Sep 21, 2012
    Thanks for that info on the UPS ScottishCaptain.

    If our power does happen to be dodgy, does it mean the UPS is probably not going to last as long either? Or are they designed to handle the fluctuations?

    I might try and get to another location TruckdriverSean. Might just be easier to get the UPS though.

    The thing that just makes me skeptical that it is a externally related power issue is that I can't turn the MP on again after it powers off. I would imagine I could simply do a SMC reset i.e. unplug it for a good while, plug it back in and power up - but it's not the case. The time I need to wait after this happens is unpredictable... sometimes straight away... sometimes 20 minutes, once a whole day. It doesn't make sense to me.

    Is there some sort of failsafe that gets triggered in cMP PSU's in case of either a brownout or overload which would produce this kind of behaviour?

    Also does anybody know if there is a log that might possibly show the reason the computer turned off?

    Today it has been 24h idle without a single hiccup in the same location.
  7. MacSince1985 macrumors 6502

    Oct 18, 2009
    The higher end UPS have a screen that displays voltage, load, capacity, etc. You could put it on your desk for a while to keep an eye on the readings.

    UPS do regulate the power by drawing on the battery when supplied power is too low and blocking power spikes like a surge protector. I suspect constant on and off would reduce it's lifespan, but the batteries are replaceable and more affordable than replacing the entire UPS.

    Some units have power conditioning features, which produce much more even current (not sure on the exact technical differences).

    This issue reminds me of what happened to many iMac G5. In that case, the internal power supply failed due to bad capacitors. I would think Apple would have tested that for you, but it's possible that a small difference in voltage is enough to overwhelm those weak capacitors.
  8. westom macrumors regular

    Nov 8, 2009
    First, time to learn about how all things work (electronics, medicine, politics, etc). Everything has perspective. That means answers must include numbers. For example, power (voltage) can drop so low that incandescent bulbs dim to 40% intensity. Even that is good voltage for all computers. How often is a bulb connected to the same wall receptacle dimming that much? If not, voltage is perfectly fine.

    With a meter set to 200 VAC setting, you can also verify that voltage between two rectangular tabs. No reason to monitor that voltage because the light bulb makes obvious any changes.

    If the bulb does dim or flicker, then trace all receptacles in that circuit. Remove the wall cover. If any have wires connected in behind (not attached to side mounted screws), then you must or get an electrician fix the defective wiring. Connection made in the back (called back stab) are legal per safety code and create problems for electronics. Safety code and good practice are not always exactly same.

    Now, that assumes a voltage drop. But a wall receptacle has three prongs. Also relevant is the voltage between all three. This is where the meter comes in handy. Voltage between a larger rectangular tab and the round safety ground tab should be above zero (when anything is drawing power on that circuit) but never greater than 2 volts. And really should not even exceed 1 volt. Also voltage between smaller rectangular tabl and safety ground should be about 120 VAC. And not vary maybe more than 3 or 4 volts with other appliances on that circuit powering cycling.

    Again, if you want answers that actually address problems, then perspective (those numbers) must always exist. Either provided in your answer. Or included in your questions.

    Finally, if a problem is in your household wiring, then computer should boot just fine in some other's house. This is an example of separating the problem into part. Then examining each part separately. Draw a line across the problem. House and AC ulitlity to the right. Computer to the left. Move everything on the left side to another venue and observe. An example of breaking a problem into parts to find the defect long before trying to fix anything.

    Meanwhile, a UPS does not do most of what others have recommended it for. It does not do magic cleaning. Obviously it does nothing useful until light bulbs dim to less than 40%. When not in battery backup mode, then it connect your computer directly to AC mains - which is what you suspect as a problem. So the UPS really does not do anything useful other than temporary and 'dirty' power during a blackout. Again, this becomes obvious once we include numbers that others have not provided.
  9. matthewtoney macrumors regular


    Aug 17, 2009
    Charlotte, NC
    Actually, as long as they were truthful with him, Apple supposedly replaced his power supply so I would assume he could count out the power supply itself being the problem.

    Like others I think the first thing I'd do is the UPS - I don't like running my Pro *not* on one anyway so it won't be wasted effort, and your hope is that if it really is power in your receptacle/breaker or whatever that instead of the Pro turning off you'll have the UPS beeping or complaining when it happens. (and if it does the same while on the UPS battery and still turns off randomly you're back to inside the box problems)
  10. Sko macrumors 6502


    Oct 17, 2009
    That came to my mind first.

    If it's not environmental failure (e.g. power, system should boot fine after occurrence, see wetsom's post) or a thermal problem (system fails in specific time frame and recovers in specific time frame), but acts really randomly, then its bad capacitors.
  11. MeloZn macrumors newbie

    Nov 5, 2015
    South Africa
    Did you find out whats the actually problem with your Mac Pro
    Im having the same issue changed power supply & still the same

    A friend suggested it could be the board
    please let me know if you have any suggestion

  12. westom macrumors regular

    Nov 8, 2009

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