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5K iMac kernel panics...

OK another update:

After a battery of memory tests on the 4x 8GB Corsair Vengeance (which, may I remind all - worked perfectly for 2 years in a 27" 2012 iMac, and for the last 6 months in this 5K iMac), all the sticks passed. NO errors of any sort.

I dug out my 2012 Mac mini and removed the OEM 2x 4GB sticks from it, which are now in my 5K iMac.

FYI, this is EASILY the most frustrating issue I've had with any Mac I've ever owned. Nothing like a kernel panic without any idea what it refers to. :(
 
WilliamG said:
OK another update:

After a battery of memory tests on the 4x 8GB Corsair Vengeance (which, may I remind all - worked perfectly for 2 years in a 27" 2012 iMac, and for the last 6 months in this 5K iMac), all the sticks passed. NO errors of any sort.

I dug out my 2012 Mac mini and removed the OEM 2x 4GB sticks from it, which are now in my 5K iMac.

FYI, this is EASILY the most frustrating issue I've had with any Mac I've ever owned. Nothing like a kernel panic without any idea what it refers to. :(
Click to expand...

Well I suggested ram for a reason. It didn't mention any kernel extensions in that core dump. It didn't mention anything that suggested peripheral hardware. You may want to check whether the specification of that ram is known to work correctly with the chipset used in these machines, because it looks like the result of a flipped bit causing an exception, which in turn causes the kernel to panic. The sticks from the mini could still be a different specification. Other than that you would have to take it into Apple. I know you both updated and reinstalled the OS, but that was the least likely problem by a wide margin.
 
thekev said:
Well I suggested ram for a reason. It didn't mention any kernel extensions in that core dump. It didn't mention anything that suggested peripheral hardware. You may want to check whether the specification of that ram is known to work correctly with the chipset used in these machines, because it looks like the result of a flipped bit causing an exception, which in turn causes the kernel to panic. The sticks from the mini could still be a different specification. Other than that you would have to take it into Apple. I know you both updated and reinstalled the OS, but that was the least likely problem by a wide margin.
Click to expand...

The specification of this RAM works just fine. :)

Also I mentioned earlier it was in use for 2 years on my 2012 iMac, and over half a year now on my 5K iMac.

The memory from the mini is exactly the same spec as the memory that's in my iMac - 1600DDR3 1.5V. I know there's some discussion on whether 1.5V is acceptable on these iMacs, but it absolutely is according to Apple, and again - 2.5 years without issue on my iMacs says everything.

It's just odd that the 4x 8GB Corsair Vengeance memory isn't showing up any issues in Memtest after 24 hours of straight testing....

In any case, I'm now running the 2x 4GB Apple OEM memory from the 2012 Mac mini since this morning, and will see if that solves the issue. It's perhaps possible that not even 24 hours of Memtest is showing up the errors in the 4x 8GB Corsair Vengeance and that it's REALLY intermittent. Who knows...?

Easy to RMA with Corsair if that turns out to be the issue.

Interestingly, I googled the kernel panic info:

Last Exception:\n\n"@/SourceCache/xnu/xnu-2782.30.2/bsd/kern/kern_exit.c:363

I came across a couple of people - all within the last month and NONE earlier that I could find. Some with completely factory hardware - with this issue. There's barely anything out there! So bizarre...
 
WilliamG said:
I came across a couple of people - all within the last month and NONE earlier that I could find. Some with completely factory hardware - with this issue. There's barely anything out there! So bizarre...
Click to expand...

That is bizarre. I was biased against the ram because of where it seemed to have faulted. You could take it to Apple, but I've never had (or seen) consistent kernel panic issues that didn't turn out to be either a piece of hardware or drivers.
 
thekev said:
That is bizarre. I was biased against the ram because of where it seemed to have faulted. You could take it to Apple, but I've never had (or seen) consistent kernel panic issues that didn't turn out to be either a piece of hardware or drivers.
Click to expand...

Right, neither have I. So we'll see how it goes with the Mac mini RAM that's in my iMac now. Usually takes about 1-3 days to kernel panic.
 
WilliamG said:
Right, neither have I. So we'll see how it goes with the Mac mini RAM that's in my iMac now. Usually takes about 1-3 days to kernel panic.
Click to expand...

That's why I thought just barely failing ram. If it's not in a critical area of memory, it won't typically cause a crash.
 
thekev said:
That's why I thought just barely failing ram. If it's not in a critical area of memory, it won't typically cause a crash.
Click to expand...

I hope so! It's annoying that RAM testing is no longer showing any issues, grrr (if that really is the issue).

Time will tell. 11 hours, 47 minutes uptime so far. :)
 
I was recently having kernel panics on my baseline 5k iMac seemingly at random. I thought it was the additional 16 Gb Crucial RAM I'd added myself, but the kernel panics kept happening after I removed the extra RAM and went back to the original 8 Gb. I finally narrowed it down to something totally crazy:

my iPod shuffle (2nd gen) recharge cable.

link: http://en.wikipedia.org/wiki/IPod_S...reen_top_view_and_dock_connector_top_view.jpg

Yep. If I leave the cable plugged into the 5k iMac, I get a kernel panic any time from 1 hour to 2 days after plugging the cable in. Once I unplugged the stupid USB to shuffle cable my iMac has been totally stable for two weeks now. nothing else has changed. It's ridiculous, but for some reason the 5k iMac doesn't like this cable at all...

The point of all this is that maybe you have some offending USB peripheral that doesn't play nice with your iMac.
 
uller6 said:
I was recently having kernel panics on my baseline 5k iMac seemingly at random. I thought it was the additional 16 Gb Crucial RAM I'd added myself, but the kernel panics kept happening after I removed the extra RAM and went back to the original 8 Gb. I finally narrowed it down to something totally crazy:

my iPod shuffle (2nd gen) recharge cable.

link: http://en.wikipedia.org/wiki/IPod_S...reen_top_view_and_dock_connector_top_view.jpg

Yep. If I leave the cable plugged into the 5k iMac, I get a kernel panic any time from 1 hour to 2 days after plugging the cable in. Once I unplugged the stupid USB to shuffle cable my iMac has been totally stable for two weeks now. nothing else has changed. It's ridiculous, but for some reason the 5k iMac doesn't like this cable at all...

The point of all this is that maybe you have some offending USB peripheral that doesn't play nice with your iMac.
Click to expand...

That is very, very weird. A cable without being plugged in to the Shuffle?
 
Sorry, just checked console, and the crash logs have already been recycled - like I said it's been 2-3 weeks since this happened. From what I remember the crashes were related to something like "[computer name]:iTunes: MUX error." Since it was iTunes related, I thought that it must be iTunes trying to talk to a USB peripheral - the only thing that was new was the shuffle cable.
I assume the USB cable has some microchip built in that handles the transition from USB to 1/8 audio jack, and my guess is that the iMac doesn't like this chip. Anyway, I haven't plugged the cable back in, and the iMac has been working fine.

I've been my old mac mini (2011) to load the shuffle instead, and I haven't had any crashing issues...
 
WilliamG said:
I hope so! It's annoying that RAM testing is no longer showing any issues, grrr (if that really is the issue).

Time will tell. 11 hours, 47 minutes uptime so far. :)
Click to expand...

Has it it panicked since then or is it still going?
 
uller6 said:
Sorry, just checked console, and the crash logs have already been recycled - like I said it's been 2-3 weeks since this happened. From what I remember the crashes were related to something like "[computer name]:iTunes: MUX error." Since it was iTunes related, I thought that it must be iTunes trying to talk to a USB peripheral - the only thing that was new was the shuffle cable.
I assume the USB cable has some microchip built in that handles the transition from USB to 1/8 audio jack, and my guess is that the iMac doesn't like this chip. Anyway, I haven't plugged the cable back in, and the iMac has been working fine.

I've been my old mac mini (2011) to load the shuffle instead, and I haven't had any crashing issues...
Click to expand...

Ahhh I should have clicked the link. It's not just a regular USB cable. Right, that makes more sense. I actually have that Shuffle in a drawer. :)

thekev said:
Has it it panicked since then or is it still going?
Click to expand...

No sir, it has not. 3 days, 6 hours, 12 minutes since switching to 8GB of RAM from a 2012 Mac mini. I'll certainly mention it here if it does panic again.

I RMA'ed the 32GB Corsair Vengeance (Express Replacement) yesterday since I don't trust it anymore (after 2.5 years of faultless performance), and the replacement shipped very quickly, - today. Will be at my house Friday by 10:30am!

I was too niggled by the fact that the RAM did show errors on both my 5K iMac and the Mac mini, - if only once...

Anyway, I'm going to leave this 8GB in till Sunday, and then swap over to the new 32GB. I really hope this solves it!
 
Last edited:
Well that was quick! I called Corsair on Tuesday, memory shipped out Wednesday from Taiwan, and first thing Thursday I have brand new memory at my door. 2015, week 17 (which is April 20-26th!).

That's pretty impressive.

I'm still going to stick with the 2x4GB I'm testing with (which is a little painful given the amount of photo work I do - but I'll survive), at least a few days longer, to make sure I've really thoroughly tested this avenue.

3 days, 22 hours, 42 minutes and counting with no crashing...
 
WilliamG said:
Well that was quick! I called Corsair on Tuesday, memory shipped out Wednesday from Taiwan, and first thing Thursday I have brand new memory at my door. 2015, week 17 (which is April 20-26th!).

That's pretty impressive.

I'm still going to stick with the 2x4GB I'm testing with (which is a little painful given the amount of photo work I do - but I'll survive), at least a few days longer, to make sure I've really thoroughly tested this avenue.

3 days, 22 hours, 42 minutes and counting with no crashing...
Click to expand...

Well memory can fail. It may have been that the errors were quite seldom. I hope the replacement works out okay.
 
thekev said:
Well memory can fail. It may have been that the errors were quite seldom. I hope the replacement works out okay.
Click to expand...

Yep that seems the likeliest explanation now. I'm sitting at 6 days, 4 hours, 37 minutes on the 2x 4GB from the 2012 Mac mini. No issues.

Once it hits 7 days I'll open up the new Corsair Vengeance packs and go back to 32GB. Hopefully that will be the last of my troubles.

Still, if this does solve it - it shows that memory tests are not exactly reliable. You'd think 24 hours of constant memory tests would reveal something (after the initial failures).
 
WilliamG said:
Yep that seems the likeliest explanation now. I'm sitting at 6 days, 4 hours, 37 minutes on the 2x 4GB from the 2012 Mac mini. No issues.

Once it hits 7 days I'll open up the new Corsair Vengeance packs and go back to 32GB. Hopefully that will be the last of my troubles.
Click to expand...

I hope so too. I mean I hope that will be the end of your troubles.

WilliamG said:
Still, if this does solve it - it shows that memory tests are not exactly reliable. You'd think 24 hours of constant memory tests would reveal something (after the initial failures).
Click to expand...

They're never 100% reliable. It's possible that nothing actually flipped during those 24 hours. They can tell you that you definitely have a problem. They can't tell you that you don't have one, yet I mentioned that it looked like one due to the location of the panic. Nothing else was really likely due to the nature of it.
 
thekev said:
I hope so too. I mean I hope that will be the end of your troubles.



They're never 100% reliable. It's possible that nothing actually flipped during those 24 hours. They can tell you that you definitely have a problem. They can't tell you that you don't have one, yet I mentioned that it looked like one due to the location of the panic. Nothing else was really likely due to the nature of it.
Click to expand...

Yep. So it goes. :)
 
OK so here's my depressing update:

I hit 7 days uptime without a crash just about 20 minutes ago. I pulled out the 2x 4GB OEM 2012 Mac mini RAM, and opened up the 4x 8GB Corsair Vengeance RAM, and put it in my iMac.

Turned it on, it booted up, - all looked great. Got into OS X, yep - all 32GB recognized. About 10 seconds later, the system froze up completely (mouse stuck) and then BAM - it rebooted. What the heck?

I boot back up - get back into OS X, I try to download Memtest, and before it even downloads, system froze up again, and then BAM - reboot again.

I turn the system off, take out the memory, put the memory I had in slots 1 and 3 into slots 2 and 4, and vice versa.

Turn system back on, and less than a minute into OS X - system froze - BAM - reboot.

So now I'm just depressed. Put back the 2012 Mac mini RAM and it's working fine.

What the heck is going on here?

*Edit*

It will crash with any combination of the sticks, even with just ONE stick in slot 1. This is crazy...
 
Last edited:
WilliamG said:
...
What the heck is going on here?
...
Click to expand...

Not too difficult to decide what happened, and what you should do (IMHO :D )

The corsair RAM is just not quite compatible with your RiMac, despite what Corsair wants you to believe. And, my thought is that you now have proved them wrong.
Maybe you can get your money back, and go with memory that you can expect will work, such as Crucial:
http://www.crucial.com/usa/en/imac-3*5ghz-quad-core-intel-core-i7-(27-inch,-late-2014)/CT6312860
- or
DataMemorySystems (DMS):
http://www.datamemorysystems.com/dm50-234e-x-2/

There's others, of course, but those are two that many folks here use, and trust. It would appear that you can say that Corsair has not improved their reputation over the years, at least in regard to compatibility with Macs.
 
DeltaMac said:
Not too difficult to decide what happened, and what you should do (IMHO :D )

The corsair RAM is just not quite compatible with your RiMac, despite what Corsair wants you to believe. And, my thought is that you now have proved them wrong.
Maybe you can get your money back, and go with memory that you can expect will work, such as Crucial:
http://www.crucial.com/usa/en/imac-3*5ghz-quad-core-intel-core-i7-(27-inch,-late-2014)/CT6312860
- or
DataMemorySystems (DMS):
http://www.datamemorysystems.com/dm50-234e-x-2/

There's others, of course, but those are two that many folks here use, and trust. It would appear that you can say that Corsair has not improved their reputation over the years, at least in regard to compatibility with Macs.
Click to expand...

Perhaps. I took the memory over to my neighbor's place. He has my old 2012 27" iMac. The memory works just fine in his system at first glance (half hour running). That's a half hour longer than it works in my RiMac (which crashes in seconds).

Corsair has some newer DDR3 1.35v Corsair Vengeance. Wonder if it's worth grabbing some of that so I can at least tell Corsair their 1.5V memory doesn't work with the RiMac 100% of the time. It's easy for me to get it.

Sigh. This whole thing is making my head spin.
 
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