Mac Pro restarts or won’t sleep

The problem

Symptoms might include:

  • Mac Pro won’t sleep, more exactly: is waking up from sleep mode spontaneously
  • spontaneous restarts or even multiple restarts
  • spontaneous, immediate shut down
  • partial and / or temporarily failing of ethernet, USB, Bluetooth and / or FireWire connections
  • gray screen of death, kernel panic
  • single applications that crash
  • RAM partially ‘disappears’, often temporarily

My Mac Pro problems

About 1,5 year ago, after a few years of almost continuous service without any problems, my Mac Pro early 2008 started to act strangely. At first, I noticed it occasionally woke up spontaneously in the middle of the night or early in the morning. It only happened a few times per month at most, making it hard to eliminated the cause. I suspected Bluetooth devices like mine and others’ cell phones, my USB printer’s nightly cleaning routine and even system settings. I disconnect the printer and tuned off bluetooth options, both of the Mac and others.

Then it would not wake up itself for weeks, so I assumed it was fixed, whatever it was.

Until I had a ‘gray screen of death’: The OS X sort of locks up because of a kernel panic and leaves you with no other option then to restart it by holding the power button. I experienced this only a few times so far but it goes without saying that this is very disturbing.

Gradually, things got worse. Not only did the spontaneous waking up reappear. Every once in a while, I have other strange problems. Usually it’s a data connection that won’t work: The USB printer printing rubbish, a USB memory stick or a FireWire connected external hard drive that wouldn’t mount, a Wacom tablet that – although connected and powered up – wouldn’t work, even my keyboard once became unresponsive.

I know a defect USB device can cause this, so I unplugged all external devices, used a different keyboard and tried to find the culprit, but to no avail.

Most remarkably, these problems usually disappeared as fast as they showed up. I soon found out that they appeared after a period of sleep. (I hardly ever really shut my Mac Pro down, usually I just put it in sleep mode.) I also found out that such problems could be fixed by briefly putting the Mac Pro into sleep mode and waking it up again.

At some point, a part of the memory was not recognized by the system any more. I did all kinds of tests, even booted from a knoppix live cd to lessen my memory footprint, in order to test as much memory as possible. I switched and finally even changed the memory modules, but I couldn’t say for 100% this fixed it.

The most common problem I have, is that it won’t go to sleep mode. (It takes after it’s owner…) That is: It goes to sleep, the fans and disks slow down, you hear the click of the power shutting of, but immediately after that it wakes up again. The fans and disks aren’t even silent yet and already the speed up again.

Oddly enough, this happens only now and then. It can happen three times in a row or more, or not for weeks. Also, it seems to happen more often when I use the OS X keyboard shortcut for sleep (CMD-ALT-⏏) than when I choose ‘Sleep’ from the Apple menu.

There are a few problems of which I am not sure they are related. My bluetooth headset sometimes doesn’t work immediately and the same counts for my external sound system. Again, turning one of them off and on usually fixes this.

The usual suspect

Online, I found quite a few similar cases of Mac Pro’s having kernel panics, sleep and wake problems, single or multiple spontaneous restarts and such, usually on an irregular basis. All kinds of strange tips are exchanged about fixing this, like reseating the memory and cleaning out dust. Although this might help some, I find it hard to believe this is for more than a few percent of the problems really the solution.

By far the most of these Mac Pro’s sooner or later end up with a failing power supply unit. Notice I didn’t use the verb ‘broken’. Often, these Mac Pro power supplies don’t break down completely. They just partially fail, or fail for a fraction of a second, over a long period of time. Maybe just once a week. As a result of this, it’s very hard to determine the power supply is the cause of this. Even if you have the knowledge and means for this, you might have to measure its performance for weeks, in order to catch it in the act.

After finding more and more stories that ended in replaced power supply units, I opened up my Mac Pro so I could check for the Apple Part Number and ordered myself a new power supply on eBay. I will update this page as soon as I think I know if this really was the problem or not.

Update 120309: Diagnostic LEDs on the Mac Pro motherboard

Close up of the diagnostic LEDs on the Mac Pro motherboardMy new power supply is not in yet, but I found out about the presence of a tiny button on the Mac Pro mother board, between the daughter boards / memory riser cards. When pressed, a set of diagnostic LED’s light up. Well, some of them, depending on the status of the machine. It’s used to help you analyze certain problems. You can look up the meaning of these LEDs. According to these, my power supply is working: The eighth LED lights up. Despite the red color, this means that the power supply is fine at the moment. I’m still not convinced though, that it is always working fine.

Update 120313: Do not use USPS

Reminder to self: Do not use USPS postal service to order packages from the US. Is it a coincidence that these are all former ‘national’ companies? It takes weeks before they deliver them. They blame Customs for it, but Customs doesn’t store packages at Schiphol, USPS and their contractor for the Netherlands, PostNL do. Also, their customer service is full of **it. Filed a complaint.

120315 The PSU finally arrives

The ‘new second hand new’ power supply has arrived, within 12 hours of my complaint. I switched the power supplies.

120316 Another spontaneous wake-up

Already the next day, the Mac Pro spontaneously woke up at the end of the afternoon. This is somewhat disappointing, because this means switching the power supply didn’t help. I checked the log file because I wanted to know what caused it. Launch the Terminal and type the following at the command line:

syslog |grep -i "Wake reason"

And it came up with:

Thu Mar 15 18:35:21 mac-pro-van-leon kernel[0] <Debug>: Wake reason = EHCI

EHC: standing for Enhanced Host Controller, is another USB interface, but can also be a wireless device or bluetooth device since they are also on the USB bus of a Mac. Bluetooth was disabled, so that couldn’t have been it. While I wasn’t even around at that moment, so I didn’t press the keyboard or (dis)connect a USB device. One of the USB devices must be malfunctioning.

Let the process of eliminating begin!

All I can do is unplug all USB devices, except for one, to see if this solves the problem. Since the problem occurs seldom, it’s hard to know for sure, but I have no other option. I decided to keep the keyboard and switch my Wacom Intuos2 for a Cintiq 12WX I had lying around. I also unplugged the USB Samsung CLX-3180FW laserprinter, although it’s very unlikely that this is the problem, since I bought it a year after the problems started.

120318 Unresponsive black screen

Today, after lunch, I returned to my Mac Pro and found it on, but with a black screen and unresponsive to keyboard strokes and (Wacom) mouse clicks. A forced restart by holding the power button was the only option. As usual, after restart everything seemed normal again. I tried a SMC reset and zapped the PRAM and wanted to go further but didn’t know how.

There is nothing harder than determine what is the problem when a machine only fails on rare occasions. If only it would break down! Then I could fix it or decide it is total loss but it would not be this agonizing.

Found it

Tonight the printer got problems again, but I know it’s not the printer. It’s the USB of the computer. This time, after half a dozen failed prints, I unplugged the Apple aluminum keyboard. Immediately, the printer started printing the page that the Mac tried to send to it, it worked fine. Then, as a dubble-check I plugged the keyboard in again, tried to print the same page again and it wouldn’t print…

Although there could always still be another problem, chances are that this was the source of my many mysterious computer problems for the last two years.

Anyone interested in a second hand Mac Pro Power supply?

120319 More Mac insomnia

The next day, my Mac again woke up by itself. It turned out to be the Apple bluetooth keyboard:

Mon Mar 19 12:26:27 mac-pro-van-leon kernel[0] <Debug>: Wake reason = UHC3

I could reset it by going to Finder/Hard Drive/Library/Preferences/SystemConfiguration and delete the and files (if your Mac asks, type your admin. password).

If the latter file isn’t present in the folder, go to user name(probably your name)/Library/Preferences, delete the file, and reboot your Mac.

In the evening it still had woken up, this time from an Apple Airport ‘magic package’ that wakes up your Mac to check for Bonjour services (really..):
Mon Mar 19 20:04:56 mac-pro-van-leon kernel[0] <Debug>: Wake reason = RTC
Mon Mar 19 20:17:32 mac-pro-van-leon kernel[0] <Debug>: Wake reason = LAN0

You can turn this off in the Energy Saver system preferences by unchecking the ‘Wake for network access’ option.

120411 More Mac insomnia

Yet another occasion of insomnia. This time it was the FireWire Apple iSight camera:

Wed Apr 11 15:30:53 mac-pro-van-leon kernel[0] <Debug>: Wake reason = EHCI

The Solution

Usually, I find the problem and fix it. It can take hours, days, months even, but in the end the satisfaction matches the build up frustration. This time I didn’t find the exact cause. Finally, I did a clean install of Mac OS X 10.7 Lion. I set back my Time Machine backup, so it’s debatable how clean this is. What counts, it that this clean install of Lion fixed my Mac Pro problems. I waited some time to speak this out loud, but now, after months of flawless usage, I am confident this was the solution to my Mac sleeping (and other) problems. Memory problems, kernel panics, gray screens are all gone!

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