# just upgraded kernel from 3.5.7 to 3.6.11 cpu overheats

## alphis

Hey guys.

I recently updated my kernel from 3.5.7 to 3.6.11 using make oldconfig (after copying old .config) and building. Another thing I did just before building the new kernel was upgrade my gcc as there was a new version. I am running x86_64 stable.

Now that I've been running 3.6.11 for a couple of days my T420 turned off due to overheating! After booting it again and running it for a while I noticed the temps IDLE at 87deg C. I then rebooted into my old kernel (3.5.7) and so far no heating issues (IDLE at ~50deg C).

My question is, is there any reason that the new kernel and/or latest gcc update could cause this kind of overheating? I'm not sure myself what the problem is as its clearly not a hardware problem as 3.5.7 runs fine without heating issues.

Any help is appreciated.

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## 666threesixes666

i run manual config (per gentoo wiki) 3.6.8?  on my laptop and 3.7.1 on my desktop and have no overheating problems.  my laptop always ran hot regardless (as its a laptop) i got midevil on the problem with a cookie sheet from the kitchen.  cookie sheets pro.  my laptop idles @ 120 F or less for some reason my laptop rejected the 3.7.1 kernel because of the geforce go6....    desktop doesnt have sensors installed but laptop did because when it compiles it will get hot enough to shut off if its on wood or flat surfaces.  it cant handle the compile after compile after compile after compile with out the cookie sheet.

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## BillWho

alphis,

I'm running 3.6.11-gentoo on a i3-2350M laptop and it's fine. The only app I have a problem with is xbmc and cpu usage.

Is there a process hogging the cpu   :Question: 

```
ps aux  --sort=-%cpu|head -n6
```

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## alphis

I just rebuilt old kernel AND new kernel with upgraded gcc (gcc version 4.6.3 (Gentoo 4.6.3 p1.11, pie-0.5.2) and the old kernel-3.5.7 still stays at a lower temp. The new kernel is definitely screwed for some reason. Its probably some new config that if not set correctly breaks everything, either that or 3.6.11 is just broken.

I'll stick with 3.5.7 for now.

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## WvR

I use 3.6.11 without any issues as far as power management etc. 

1. check for running processes with top - if there is some process running 100% full time then that is the source of your problem

2. check that the CPU throttling software works (i.e. check /var/log/messages for any hints of warnings or errors)

3. rebuild acpid

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## Veldrin

I had a similar issue but with kernel 3.7: while the CPU was idle, temperature would rise to a dangerous level.

using powertop, I was able to find out, that not the CPU, but the GPU was not able to sleep, and staying fully powered. 

I am not sure what caused it, upgrading to the latest version seem to have fixed it. 

If it does not help, you could at least install powertop 2 to figure out if the CPU or the GPU is causing the problem.

V.

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## alphis

I just installed powertop (very cool program btw) and it says the following during idle:

Cn                Avg residency       P-states (frequencies)

C0 (cpu running)        (100.0%)      Turbo Mode   100.0%

polling           0.0ms ( 0.0%)         2.50 Ghz     0.0%

C1 halt           0.0ms ( 0.0%)         2.21 Ghz     0.0%

C2                0.0ms ( 0.0%)         2.00 Ghz     0.0%

                                        1.80 Ghz     0.0%

So uh....one core seems to be at max at all times... 

How do I fix this?

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## alphis

I just rebuilt my kernel with CONFIG_PM_RUNTIME (and CONFIG_TIMER_STATS) as suggested by powertop itself and my CPU usage is now way better (avg 2.8%). 

Thanks much for the help! I'll rebuild 3.6.11 with the same thing and that should resolve the problem.

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## Chiitoo

Figured I'd mention the CPU governor even if that might not be the reason of distress in your case.

Might be rather obvious, but I'd check that the default one isn't set to performance for example.  In any case, the poor machine sounds like something that could use a spring-cleaning, or something of the likes!  Perhaps replacing the thermal grease wouldn't be a bad either either.

I mean, unless it's of very poor design, it shouldn't get that hot in the first place, right!?

Reminds me of how I some days ago, mentioned to a friend how I was rather surprised that a 10 year old laptop I've been testing Gentoo on, has not overheated to that extent (as of yet).  Not too many minutes after that, though, it shut down!  However ironic that would have been, it was only due to forgetting to connect any extra power to it.  (Its battery is pretty dead, although fully charged it still lasts an hour or two... or more... but I digress!)

I hope you got it figured out!

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## alphis

So I added the runtime_pm to kenrel 3.7.9 which is now out and like 3.6.11 I am having severe heating problems! Runs at 90 deg C on IDLE!! I switched back to 3.5.7 again and am running at 57 deg C under fair workload. 

Obviously its not the hardware, its the kernel. I dont know what changed but its breaking my system. The CPU scaling governor is set to performance on every single kernel I have ever built. That is not the problem. Incidentally I switched it to ondemand for 3.7.9 just to see and it still went to 96 deg C on IDLE. 

I'm not happy with how this is going as I simply cannot upgrade my kernel from 3.5.7 until I can determine what is causing this issue. I'm all ears if anyone has any ideas.

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## _______0

which proc?

You should follow power management guides too. Things don't configure themselves magically.

If it's a laptop check you don't have a thick layer of felt in your dissipator.

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