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I think my 27" Late 2013 memory is overheating :\

T

tseven

macrumors newbie
Original poster
Oct 5, 2013
6
1
Conclusion/Update Fri, Oct. 11:

I performed additional testing while swapping the location of each chip. According to Temperature Gauge, the Memory - TM1a maxed out at 260F which was higher than the software's visual meter went. The only thing which reduced the temperature was running 2 sticks instead of 4 and running the machine with the ram door removed. Neither the back of the machine nor the ram chips ever felt hot to the touch.

Monitoring the memory temp using XRG during the stress test didn't raise any alarms. Temperatures seemed normal.

For peace of mind, I had my local Apple store checkout my iMac with the memory I purchased from Crucial.com. They ran a battery of comprehensive tests on it over night (14+ hours) and the system is 100% fine. I was told there is no reason for concern.

My conclusion is that Tunabelly's software is not reading the memory temperatures accurately.

I posted pictures of the ram I bought from Amazon.com, Crucial.com and the stock memory that came in the machine.

The memory I bought from Crucial.com was an extremely tight fit. It took some caressing to snap into place. Removing the memory will be near impossible without a tool.

I've decided to keep the memory I bought from Crucial.com since it looks like the they will charge a 20% restocking fee. My guess is the ram from Amazon.com is 100% fine.

----------------------------------------------

I received my new iMac last week and noticed something strange when maxing out all the CPUs while running Prime95
According to Temperature Gauge by Tunabelly Software the Memory - TM1a redlines and reaches 220F+ (104C).

1gf59MP


The screen shot above was taken when the iMac was idling. The black lines to the right indicate the max temp that was reached under stress.

Apple user Baltwo experienced a similar issue which was caused by a faulty fan.

I'm worried my iMac may have a faulty fan or something.

The app only see's one fan.

Can anyone else running the a Late 2013 27" iMac replicate these results? I'd love to know if I should have mine checked out.

1gf7xDh


Any thoughts or suggestions will be appreciated.

Thanks
 
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Was the memory supplied by Apple or did you upgrade it yourself?

I've been looking for RAM to upgrade my iMac on order, and I've read some reports that Haswell machines require 1.35V memory instead of the more common 1.5V. There is conflicting advice online, but there is a suggestion that using 1.5V RAM could cause overheating. Recommended memory upgrades from Crucial and OWC are now 1.35V and I'm sure that Apple memory is also now 1.35V.
 
I don't understand stress tests and measuring CPU temps at all. Why not just use the thing and then there's always AppleCare if it explodes?

I'm not trying to be rude, just thinking aloud.
 
Erphern said:
I don't understand stress tests and measuring CPU temps at all. Why not just use the thing and then there's always AppleCare if it explodes?

I'm not trying to be rude, just thinking aloud.
Click to expand...

My thoughts exactly. Unless of course you changed the memory yourself, in which case you might want to put the original stuff back and see if it gets as hot. Failing that, just enjoy it :-D
 
ian2000 said:
Was the memory supplied by Apple or did you upgrade it yourself?

I've been looking for RAM to upgrade my iMac on order, and I've read some reports that Haswell machines require 1.35V memory instead of the more common 1.5V. There is conflicting advice online, but there is a suggestion that using 1.5V RAM could cause overheating. Recommended memory upgrades from Crucial and OWC are now 1.35V and I'm sure that Apple memory is also now 1.35V.
Click to expand...

Good catch. I did upgrade the memory myself. I installed this Crucial memory which is rated as 1.35V.


Erphern said:
I don't understand stress tests and measuring CPU temps at all. Why not just use the thing and then there's always AppleCare if it explodes?

I'm not trying to be rude, just thinking aloud.
Click to expand...

I appreciate the input and don't think it's rude at all :) The reason I'm stress testing this iMac is because I'm still using my old one and haven't fully transitioned yet. If my new one needs new ram or repairing, now is most convenient time since it won't affect my ability to work. It would be a real bummer if the new iMac burns out while encoding a movie or something after I sell the old one.

jg321 said:
My thoughts exactly. Unless of course you changed the memory yourself, in which case you might want to put the original stuff back and see if it gets as hot. Failing that, just enjoy it :-D
Click to expand...

That's a good idea. I'll give that a shot.

Thank you all for your input.
 
It's also possible there is a HW issue like a faulty sensor or a software issue like a fan threshold set to high. Can you feel the heat on the back of the screen/case, particularly after say 10 min at max?
 
tseven said:
I appreciate the input and don't think it's rude at all :) The reason I'm stress testing this iMac is because I'm still using my old one and haven't fully transitioned yet. If my new one needs new ram or repairing, now is most convenient time since it won't affect my ability to work. It would be a real bummer if the new iMac burns out while encoding a movie or something after I sell the old one.
Click to expand...

That makes sense to me. Thanks for explaining!
 
ElectronGuru said:
It's also possible there is a HW issue like a faulty sensor or a software issue like a fan threshold set to high. Can you feel the heat on the back of the screen/case, particularly after say 10 min at max?
Click to expand...

I felt the back of the machine after the stress tests and it wasn't hot. It was mildly warm. The warmest part was the stand where it meets the back of the display.


I replaced the Crucial memory I installed with the stock memory that came with the iMac and there is absolutely no overheating.

Stock memory 10+ minutes
1a3CzI7


The Crucial memory I bought reached 224F within a matter of minutes.
18IapnZ


I'm not brave enough to let the Memory TM1a stay at that temperature for more than a minute. I'm assuming the temp would continue to rise if I let it.

I tried shuffling the memory around to see if there was a configuration which didn't over heat, but it didn't make a difference.

When I only used 2 of the 4 Crucial sticks, the temperature maxed at 209F. It appears having 4 chips reduces the air coming from the fan.

I think I may return that set of Crucial memory I found on Amazon and buy the memory Crucial recommends for my system. The memory Crucial.com recommends is $50 more. But if it doesn't overheat I'll be able to sleep better at night :D

I thought the memory would be fine since all the specs matched. Maybe the Haswell chipset is super picky or something.
 
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I think my 27" Late 2013 memory is overheating :\

What is the difference between the RAM from amazon and crucial? Isn't the amazon one just cheaper?

I'm worried now as I bough the CT2K8G3S160BM kit from amazon
 
Musio, RedReplicant is probably right, chances are the memory I received is off in some way.

The replacement ram I ordered from Crucial.com should be arriving in a week or so.
I'll report back with more news then.
 
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The thermistor on that ram stick could also be faulty. Try reordering the Crucial ram to see if the hot one moves around. If it does, that ram may be reading a faulty number, but still be usable.
 
Intell said:
The thermistor on that ram stick could also be faulty. Try reordering the Crucial ram to see if the hot one moves around. If it does, that ram may be reading a faulty number, but still be usable.
Click to expand...

While this may be the case and a neat thing to test I think he should be returning the sticks.
 
Not trying the thread jack but I was wondering if its a bad idea to mix DDR3 PC3-10600 and DDR3-12800. My 2013 27" iMac came with 8gb of 12800 but I had 16gb of 10600 so I threw it in. I haved seen any issues and its been about a week. System says all four slots contain 1333.
 
RedReplicant said:
While this may be the case and a neat thing to test I think he should be returning the sticks.
Click to expand...

Especially since he bought the wrong part number for our model computers. Amazon needs to be updated because those sticks are obviously not for our machines. Crucial says its CT4951624, not CT2C8G3S160BM.
 
buster84 said:
Especially since he bought the wrong part number for our model computers. Amazon needs to be updated because those sticks are obviously not for our machines. Crucial says its CT4951624, not CT2C8G3S160BM.
Click to expand...
Our machines are not special snowflakes. They are both 1.35v DDR3-1600 with 11 CAS Latency (12800 / 8 is.... 1600). Crucial does weird part numbers for every different application.

You can go buy any 1.35v DDR3-1600 CL11 SODIMMs and they will work fine.

KOTULCN said:
Not trying the thread jack but I was wondering if its a bad idea to mix DDR3 PC3-10600 and DDR3-12800. My 2013 27" iMac came with 8gb of 12800 but I had 16gb of 10600 so I threw it in. I haved seen any issues and its been about a week. System says all four slots contain 1333.
Click to expand...

10600 is marketing rounding retardation from 10666 which when divided by 8 bits = DDR1333. It'll run slightly slower but you'll never notice the difference.
 
RedReplicant said:
Our machines are not special snowflakes. They are both 1.35v DDR3-1600 with 11 CAS Latency (12800 / 8 is.... 1600).

10600 is more or less 10666 which when divided by 8 bits = DDR1333. You'll be fine.
Click to expand...

Did you design the ram, are you the company who designed the ram for this specific computer? This is a haswell specific machine not a 2012 machine that these might work on. I'm sorry but Crucial would not have a compatibility chart with only the CT4941624.

I also wouldn't spend 2-3k on a computer to cheap out and stick ram in my computer that is the wrong part number. The op didn't know, but you're blantfully telling people that its ok. It is not ok. If you want to risk screwing up your expensive machine go right ahead. Apple logs all hardware Id's and links it to your apple account. If repair reps are smart enough to look that up they will see that you used incompatible ram thus voiding you warranty you wont get it fixed for free, but hey its your computer do as you wish.

Just don't come on here telling people that might not know anything (or a little) about computers and let them think its ok to run ram thats not on the comparability list. If it was compatible it would be on the Crucial list of compatible ram. It is NOT. Their is a lot more that goes into the design and compatibility of ram other than the specs you see on the for sale page.
 
buster84 said:
Did you design the ram, are you the company who designed the ram for this specific computer? This is a haswell specific machine not a 2012 machine that these might work on. I'm sorry but Crucial would not have a compatibility chart with only the CT4941624.

I also wouldn't spend 2-3k on a computer to cheap out and stick ram in my computer that is the wrong part number. The op didn't know, but you're blantfully telling people that its ok. It is not ok. If you want to risk screwing up your expensive machine go right ahead. Apple logs all hardware Id's and links it to your apple account. If repair reps are smart enough to look that up they will see that you used incompatible ram voiding you warranty, but hey its your computer do as you wish. Just don't come on here telling people that might not know anything (or a little) about computers and let them think its ok to run ram thats not on the comparability list. If it was compatible it would be on the Crucial list of compatible ram. It is NOT.
Click to expand...

Crucial's list has been out of date and inaccurate in the past. Wouldn't surprise me at all if that was the case here. Both of those ram types are within Intell's spec limits as being compatible.
 
RedReplicant said:
Why is Crucial's list the gold standard?
Click to expand...

Intell said:
Crucial's list has been out of date and inaccurate in the past. Wouldn't surprise me at all if that was the case here. Both of those ram types are within Intell's spec limits as being compatible.
Click to expand...

That may be the case, but you guys can do as you wish with your computers. I'm sure people would rather know for sure that their ram is the correct ram.

This argument is just like the hackintosh argument. You can get the same thing as an imac by building your own, but the reason you pay 2-3k is for apples engineering, style and support and guaranteed compatibility. If your going to throw ram in thats from another company that is not on the comparability list you might as well go buy a computer and make a hackintosh.
 
buster84 said:
That may be the case, but you guys can do as you wish with your computers. I'm sure people would rather know for sure that their ram is the correct ram.

This argument is just like the hackintosh argument. You can get the same thing as an imac by building your own, but the reason you pay 2-3k is for apples engineering, style and support and guaranteed compatibility. If your going to throw ram in thats from another company that is not on the comparability list you might as well go buy a computer and make a hackintosh.
Click to expand...

Therefore, what you're saying, is that you should let Apple handle the memory upgrade for you? They are the one with the true compatibility list, after all.

Look man, iMacs use an Intel chipset, DDR3 memory, and a Haswell processor. This is all standardized. It's not a special computer. Go pick some memory that matches the speed and timings of stock and you're perfectly fine.
 
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