# My CPUs hit 114 degrees C!!

## kimmie

Hey, check this:

I have an old (like, 9 years old) dual PIII that I use as a server and sometime desktop. I usually leave gkrellm running on my laptop, monitoring this machine. Not for any good reason, just because I like to   :Rolling Eyes: . 

So the other day I noticed that the fans were reading all over the place. And the CPUs were at 108 degrees and 114 degrees celcius. I didn't believe it, so reloaded the sensor module. Same. I still refused to believe the readings. I was about to go home anyway. When I got home, I went to the machine, felt a bit warm, nothing more than on a very hot day. But the case was a little warmer right near the CPU's so I opened it up (without turning the machine off, it's a good case like that). 

Both the CPU fans had stopped. It smelled a bit cooked. Also, there's an extra exhaust fan that's supposed to trigger when the CPU's get too hot (this is set in the BIOS), and that fan hadn't turned on. It was working last time I checked. 

I rebooted it, and... no problem, back to normal. But I need to be able to leave this machine on, it's no good if it's about to set my house on fire!!! And I was under the impression that, you know, it would shut down by itself instead of going thermonuclear. Not to mention, it's NOT SUPPOSED TO TURN OFF IT'S OWN CPU FANS!! I googled a bit, and the only thing I could come up with was that there was some sort of conflict between lm_sensors and kernel ACPI, which had resulted in some control registers getting borked and turned off the CPU fans. Nice. I had acpi THRM enabled in the kernel. I don't really use ACPI to monitor it, because it's  broken, only deals with one fan/cpu and no voltage settings. I checked the logs, there was no acpi info except at boot (THRM for one of the cpus). So I rebuilt the kernel with the only ACPI module being the power button.

Then I poked around in lm_sensors a bit, I hadn't used any set commands to set fan and temperature limits, because the defaults printed out by the sensors command (which came from the BIOS, I checked that) were ok. But it seems that lm_sensors had somehow turned OFF any actions that triggered when the limits were hit. When I put the set commands in sensors.conf (setting the same limits it was printing out anyway) and tested, I could make the overheat fan come on. And the CPUs slow down too, this is pre-speedstep days, but the motherboard does something drastic, I'm not sure how this works. (Maybe that had still come on the other day and that was why the machine was still up, rather than fried, I don't know). 

Anyway, I have a half-assed theory (ACPI/lm_sensors conflict) about how the fans got turned off. And I've fixed up the triggering of the overheat fan, and the CPUs go into slowdown if they get too hot. I can only hope it doesn't happen again. 

I posted this partly because I thought the story deserved a a spot in the geek chronicles. But if anybody has any thoughts  :Idea: , that'd be good too.

PS. Oh yeah, I also found a funnel web spider had set up shop in the power supply. I kid you not. The big end of the funnel spans the intake slots on the top of the power supply, then the web tightens up through a choke point, and fans out again, finishing neatly around the edge of the exhaust fan. What does this thing live on, dust? It's a very sparse web which you'd expect for it to survive the airflow. Perfectly designed! What a guy! Go spidey! Anyway I couldn't be bothered opening up the power supply and that spider (if it was still there, I couldn't find it, but the web looked fresh) obviously had heaps charisma and dexterity points, so I didn't want a confrontation. Good luck to it!    :Laughing: 

[edit, PPS. while I'm writing huge rambling posts: I really get a kick out of the fact that Gentoo lets me run a functional desktop on this old beast. I even get metacity compositing, I like those transparent terminals and shaded window borders. I can play descent on it at 60fps+ with an old style (huge) gameport joystick, while it's doing an emerge -NuD world. Well, with the right nice/ionice settings. What more could you want? Eat dirt, XP. Anyway, you get the point.]

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## audiodef

Now that is just all kinds of cool, especially about the spider.   :Cool: 

Computer airflow generally works by sucking. But what about pushing filter air into and through the machine instead? This gives you a clean airflow, and probably a higher/cooler/quieter airflow. Check out what I did with a ProLiant:

http://blog.audiodef.com/2010/01/adventures-in-creative-computing-vol-1.html

It actually looks a little neater and cleaner now because I've taken the tape off the front and added a 2-inch stack to the hole so I can put the dryer hose in without fear of scraping against any internal parts.

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## droozer

It sounds like your processor is just REAL worried about going into electron freeze out.  I think you have successfully fended off that threat! Well done!

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## kimmie

audiodef: Hey, good job!!! Nothing like a good hack! So is that fan really quiet enough that you can work in the studio with it running? Do you live record? Is it quiet enough for that? I use my laptop as a studio machine cause it's quiet and I record acoustic piano from the same room; I have to use rubber door seals instead of feet on the external hard drive so it doesn't make the desk hum. But the laptop's getting a bit long in the tooth, I've been thinking about building a new machine. You've given me a great idea: passive cool the CPUs and use a humungous fan. Thanks!

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## audiodef

I'm glad to have a positive and creative influence. 

Yes, the fan I got is really quiet enough. It's 0.3 sones. You can get fans that are even quieter. Right now, the only audible noise is the noise from the power supply fans inside the computer, which I have not figured out how to disable yet because of the fail-safes that won't allow the machine to power on without them, despite the fact that sufficient cooling and air flow exists from the external ventilation fan. I can record acoustic guitar with this machine running, and I only need to be a few feet away for the noise not to interfere with the recording.

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