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iMac 24" alu shuts down for no reasons

V

virusbeatbox

macrumors newbie
Original poster
Sep 3, 2012
14
0
Hi,

I'm experiencing problems with my 3-year old 24" inch iMac aluminum. The first time he shut down, I was Skyping with my girlfriend.
While working on it, it shuts down for no reasons. Sometimes it shuts down while browsing the internet, watching video on YouTube, sometimes just by going to the widgets. This is what I've done so far (these didn't fix the problem):

- Booting in OS X from external HDD (verifying if it was HD related)
- Replaced RAM with brand new ones
- SMC reset, PRAM reset, VRAM..
- Several Apple Hardware Tests, short and extended for several hours (no problems found). Note that the iMac NEVER shut down while performing these tests.
- Full clean install on the internal HDD itself
- Performed Repair Disk and Disk Permissions
- Created new user, logged in with that account (no luck either)
- Checked the Power Cord for any damage AND switched to other wall sockets
- Installed smcFanControl and turned the fans to full speed so it got cool enough (still shutting down)
- Installed SystemLoad and performed those tests while monitoring the temperature with TemperatureMonitor. Check screenshot for the temperature values: http://dl.dropbox.com/u/42974675/Screenshot.jpg

Hope anyone can help me try and fix this. I'm still a college student and need my computer for all my work. Besides, now my iMac is out of warranty, if i want to let them fix it, I'll have to pay a lot I guess :(

Thanks a lot in advance!

PS: If someone is experienced enough and kind enough to help me, I have saved the Console logs when he shuts down. Maybe someone can have a look at them to see the problem can be found there?
 
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You've done a lot already....might want to try opening it up and blowing out the accumulated dust. I know you've turned the fans to max, but if there's a layer of dust sticking to a critical component, it'll act as an insulator and just because there's more air blowing around, it won't cool properly.

Sounds like a heat problem to me - but with all you've done, if a good cleaning doesn't work it could be a solder joint or board trace opening up when things heat up - and that would be expensive to fix unless it's super-obvious by visual inspection.
 
Thanks for the reply!

Was also thinking of some dust inside, unfortunately i don't have those torx screw drivers, I'll go to the hardware store later today (or tomorrow) to buy some.

If someone else has idea's, I'm all ears!
 
The log looks like it's not fully starting up - it does report an odd error with an NTFS volume...might try unplugging the volume with ntfs on it.

It's not a kernel panic or application crash that I recognize though.
 
old-wiz said:
The log looks like it's not fully starting up - it does report an odd error with an NTFS volume...might try unplugging the volume with ntfs on it.

It's not a kernel panic or application crash that I recognize though.
Click to expand...

Say what? That's strange, I really don't have any volume plugged in that's NTFS. The only volume was in that time was my USB but that's formatted exFAT.

The strangest thing to me is, that he shuts down while performing a small graphic performance. Like when watching youtube videos or going to the widgets. But when I perform Apple Hardware Tests, it keeps doing those tests for hours without shutting down. I really have no idea what the problem can be.

Gonna try opening it asap to clean out the fans and look for any dust particles and loose hardware maybe.
 
I'm gonna go out on a limb and guess that either (a) your hard drive needs repartitioning, (b) your hard drive is slowly going bad and it's not yet bad enough for tools to detect it, or (c) your main logic board is starting to go bad. Obviously, you should try to address it from (a) to (c) as your fixes become more invasive from there. If it's your logic board, then there's no point in repairing your iMac as a similar vintage iMac will cost you comparable to the cost of the logic board, effectively totaling your computer. Best of luck!
 
Yebubbleman said:
I'm gonna go out on a limb and guess that either (a) your hard drive needs repartitioning, (b) your hard drive is slowly going bad and it's not yet bad enough for tools to detect it, or (c) your main logic board is starting to go bad. Obviously, you should try to address it from (a) to (c) as your fixes become more invasive from there. If it's your logic board, then there's no point in repairing your iMac as a similar vintage iMac will cost you comparable to the cost of the logic board, effectively totaling your computer. Best of luck!
Click to expand...

Thanks for the ideas.

I understand what you mean in terms of my HDD getting bad or anything but, as I said in my first post, I installed OS X on an external HDD and at start up booted from this external HDD yet still the iMac shut itself off. So, can I state that the problem isn't caused by my HDD?

Thanks
 
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virusbeatbox said:
Thanks for the ideas.

I understand what you mean in terms of my HDD getting bad or anything but, as I said in my first post, I installed OS X on an external HDD and at start up booted from this external HDD yet still the iMac shut itself off. So, can I state that the problem isn't caused by my HDD?

Thanks
Click to expand...

Sometimes the drive still being connected will cause issues even if you aren't booting from it. Again, it is obviously prudent to rule out any issue here before calling it a logic board issue, but barring that, it sounds like a logic board issue.
 
A few hundred bucks. The thing is that those power supplies aren't freely available. Only from Apple or via eBay. If you get it via eBay it won't be that costly.
 
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