My daughters McBook Pro (medio 2012) running OSX 10.10 suffers from 2 huge problems:

1) From time to time the computer seem incredibly slow in operation although CPU is 95-99% idle according to activity monitor

2) Fans and CPU stays on during sleep, leaving the chassis very hot and draining the battery

Problem 1) is very much on and off. It seems to be (relatively) fine after boot and even after "sleepmode" (although that only works partially), but after some time it degrades heavily. I still have no idea about the which amount of time / workload should pass before it degrades, but it does.. Sorting entries/changing panes in activity monitor, opening the apple menu, opening power settings, changing active window etc. goes from instant reaction to many (10-30) seconds of wait-time (with the strange colored working-wheel), and sometimes no reaction at all. Strange pauses many seconds when navigating in menus, again with the strange working-wheel

Problem 2) is 100% consistent and relatively new (few days) Being the most consistent issue, I concentrate a lot on problem 2), although problem 1) is much more serious when it pops up:

When closing the lid for sleepmode, Sleep Indicator Light (SIL) turns solid and stays solid, which should mean DISPLAY sleep (https://support.apple.com/en-us/HT203576). Strange!!??

However, the fans stay (and cpu) stay on. If left for several hours with no A/C-cord connected, the chassis (back bottom) turns very hot and the battery drains. When waking it up, I can see from CPU history (double-click the CPU-graph in activity monitor and let both run during sleep) that the CPUs have been running with high load during sleep!? Very Strange!!??

With terminal (grep'ing for 'Sleep' and 'Wake' in pmemset -g and a shell while loop with a date-command and a short sleep) I can see that it IS actually sleeping - but the CPU is running!!!???

In my System.log the last 20-ish log-enties, ending with 'hibernate_write_image done' and 'sleep' are logged (dated) at the time of wakeup, but I guess that is just a buffering issue...

When waking up, the fans turn off for a second or so and SIL is blinking once right before screen is turned on.

I have Reset SMC (I think - how do you know if it actually did anything other than making you look ridiculous using something resembling an IBM-grip on a Mac?)

I noticed that all power settings (Apple menu > System Preferences > Energy Saver) were set to "never". I lowered them all to a few minutes. It seems like display sleep works, turns on SIL to solid, fans stay on, and it can be cancelled with pushing the power button a single time(not with mouse pad!?) If I wait the time set to machine sleep, there is no change: SIL is solid, fans running. But after that it is harder to wake up; clicking on mousepad and pushing power button several times?? According to pmemset it has been sleeping and cpu load has been high during sleep (strange sentence!) as above. I.e. the energy saver sleep reacts exactly as closing the lid.

Using apple menu -> sleep yields exactly the same behavior as the two other methods.

From other threads I know of 2 possible possibilities: 1) cleaning fans. 2) replacing HD-cable. I will try them in that order, when I get the proper tools and spare parts, although I don't really believe #2...

Any other ideas??

  • Maybe make sure WOL (wake on LAN) is off and try put hard disks to sleep in energy saver sections of system prefs. – bret7600 Aug 25 '16 at 0:44
  • Have you tried updating the Mac to the latest version of OS X? – At0mic Aug 25 '16 at 3:50

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