[ale] laptop running very hot!

[Ron Frazier]

Jim,

Forgive me if I say anything too obvious, but I, too have had some 
issues with frying laptops. Not totally sure if yours is a laptop, but 
desktops are similar. I cannot speak to F15 specifically, these issues 
are more generic. First, I would check the BIOS. Look for anything 
related to fan speed or cooling. Disable anything like smart or adaptive 
cooling and set to maximum cooling mode all the time. Make sure you 
don't disable the cooling system though. If you can select fan speeds, 
set them all to 100 % at all times. Once you solve the cooling problem, 
you can go back and worry about noise if you want to. Note that the OS 
may override the BIOS, but you don't want the BIOS to be part of the 
problem.

You need to determine the maximum CPU temperature the laptop can take. 
You cannot assume they're all the same. The Intel Core 2 Duo chip in one 
of my laptops can take 100 deg C. The AMD Phenom II X4 chip in my 
desktop can only take 62 deg C. The old Pentium 4 chip in another laptop 
can only take 71 deg C. Finding out the max temp rating is not always 
easy, and reading a processor spec sheet, even if you can find the right 
one, can drive you bonkers. These links may be of help.

I don't even know how I found theses, and I had some better ones at one 
time, with simplified lists of chips and temperatures, but I cannot find 
them. (Somebody else can jump in and tell how to discover exactly what 
chip you have out of the hundreds of SKU's.)

For Intel:

http://ark.intel.com/Default.aspx
click processors
click (for example, for my old laptop) Pentium 4
click the box that says "Show spec, stepping, ordering, and socket details"
find the right chip somehow (In Windows, you can right click on your 
"computer" icon and select properties to get some processor data. I 
cannot remember at the moment how to get more detail.)
for this example, I chose Intel® Pentium® 4 Processor 2.40 GHz, 512K 
Cache, 533 MHz FSB
click the link for the chip
look for the Tcase spec, which in this case is 71 deg C
consider that your upper limit temperature

Now, if your sensor is reading junction temperature, that may be 
somewhat different, and maybe a bit higher. However, if you consider the 
case temp spec as your upper limit, you'll be fine regardless.

For AMD:

http://products.amd.com/en-us/
doing a processor example, click desktop processors
select (for my example) HDZ965FBK4DGM AMD Phenom™ II X4 965
click view detail
look for the max temps spec, which in this case is 62 deg C
consider this your upper limit temperature

(Do you know how hard it is to keep a 4 core chip to 62 deg C or less 
under load?! I had to resort to liquid cooling.)

Before testing, verify that the fan intake is open and free of lint and 
dust. Many laptops have the fan directly on your leg, if it's in your 
lap, or directly where it will be blocked on a bed, etc. Don't operate 
on any surface which blocks the intake. Fluffy or fuzzy surfaces are 
awful. Also, these accumulate lint and dust over time which is very 
fine. I ended up putting a piece of wedding ribbon over my fan intake to 
prevent this. I've heard that panty hose fabric works too. A regular 
foam filter pad, like on the back of a space heater, may be too course, 
as the dust I'm describing is very fine. Depending on the case design, 
desktop fan intakes can accumulate lots of dust in little grill holes too.

Load something like SpeedFan in Windows to check the CPU temperature. 
Start Windows and put the machine under load with a CPU intensive task 
like a video conversion or something. You can also use the Prime95 
program in either Windows or Linux to exercise the system. 
http://www.mersenne.org/ Run the CPU full blast and make sure the CPU 
never exceeds the maximum temperature you discovered. In a room that's 
under 80 degrees F or so, it should be able to run continuously at 100% 
load without exceeding the spec, although it may get close to it. If 
needed, set the power settings to maximum and / or active cooling, which 
varies the fan speed instead of just the processor speed. Also, to 
properly test it, make sure the CPU actually goes to 100%. If it 
doesn't, you may have to adjust the power settings to allow it. You can 
observe the CPU graph in the performance tab of task manager.

If it overheats in Windows, verify that the fan is either running at 
full speed all the time or verify that it ramps up to full speed under 
load. Verify that there is a decent breeze of warm air coming from the 
heat sink where the processor is. If the fan is on, and the intakes are 
clean, and it still overheats, there may be a blockage on the inside of 
the case. My Dell laptop was overheating under load one time. I had to 
take the access cover off the bottom and look at the processor heat sink 
radiator, which is connected to the CPU and GPU via a heat pipe. There 
was a glob of dust blocking the radiator from the INSIDE. It was totally 
invisible from outside the computer. I had to remove the entire radiator 
and heat pipe assembly, clean the dust, then replace them carefully. I 
didn't have to reapply the thermal paste, but that's something you may 
have to consider. After that, my CPU temp never gets above about 75 deg 
C and that particular PC has a limit of 100 deg C. I keep SpeedFan 
running with a little icon in the system tray that lets me check the 
temp at a glance.

Once you know that the BIOS is OK and that the physical parts of the 
cooling system are working properly, you can reboot into Linux and 
troubleshoot. Set up LM Sensors or whatever package you need to monitor 
temperature. You may have to install a kernel module to get the sensors 
to work, depending on the motherboard. You can put a CPU Temperature 
applet on the Gnome panel so you can read it whenever you want. Go 
through the same drill. Start the system under Linux, put it under load, 
and observe the temperature. If the unit has been moved, make sure the 
fan intake is still clear. Make sure that the fan either runs all the 
time or ramps up when needed. As before, set the OS power settings to 
maximum and / or active cooling. I don't know how that's done in Fedora. 
In Ubuntu, you can use the System Monitor application or the CPU 
Frequency Scaling Monitor Gnome Panel applet to monitor CPU frequency. 
System Monitor can also monitor processes. You may not be seeing all 
processes with TOP. System monitor is graphical and has scroll bars. I 
think HTOP will provide a more comprehensive list in a terminal screen. 
Run it at 100%. When looking for rogue processes, be sure to look at 
both user processes and system processes. I say again, you SHOULD be 
able to max out the machine without overheating it. If everything is 
running properly, it should literally be impossible for you to overheat 
it. Having said that, running at close to "redline" for any machine will 
reduce longevity and reliability, so I don't recommend it unless you're 
testing or doing some task that requires full power.

Good luck.

Ron



On 6/24/2011 3:49 PM, Jim Philips wrote:
> I have an HP DV7 4060-us. On Windows 7, it never runs more than 
> lukewarm. But on Fedora 15, running KDE, it gets blazing hot even when 
> it's sitting idle. If I run top, I don't see more than 6% CPU 
> consumption. On one occasion, it got so hot I started having hardware 
> failures, but the damage wasn't permanent. Obviously, I'm now scared 
> to leave F15 running for any length of time. Are there any diagnostics 
> I can run that would tell me what's going on?
>    

-- 

(PS - If you email me and don't get a quick response, you might want to
call on the phone.  I get about 300 emails per day from alternate energy
mailing lists and such.  I don't always see new messages very quickly.)

Ron Frazier

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linuxdude AT c3energy.com