Bizarre CPU temperature behaviour

Discussion in 'Hardware' started by Death Zebra, Feb 15, 2011.

  1. Death Zebra

    Death Zebra Private E-2

    I've been having some temperature problems and eventually discovered that my CPU temperature reads as 71C when I turn it on (I've been going to the BIOS everytime I turn it on to check) sometimes wheareas others it seems to be (what I think is) the normal temperature of about 30C.

    Below are the readings I took when it apparantly started hot yesterday (the BIOS said it was 71C). The 54C maximums shown for core temperatures are from running CPU Stability test for 5 minutes (might have been 15 minutes but it doesn't matter since the results are the same). The CPU temperature barely increased despite the test putting it at full load and never gets beyond 74C. I opened the case when it started hot last week and the temperature didn't drop below 71C. Also, both fans were running fine. Oddly enough, when it starts hot, neither the case nor the air coming out of the vents feels any hotter.

    [​IMG][​IMG][​IMG]

    Below are the readings I took after I turned the computer off and then turned it back on appoximately 45 minutes later. IIRC the CPU temperature in the BIOS was 28C, possibly 30C. For some reason I took the readings before running CPU stability test though I do remember that the cores and CPU temperatures stayed at around 52-54 when running the test and then quickly dropped to the low 40s when I stopped the test after 15 minutes and then to the early 30s after about 30 seconds of doing nothing.

    [​IMG][​IMG][​IMG]

    Any ideas what could be going on?
     
  2. onegoodman

    onegoodman Private First Class

    How old is the computer in question? If its more than two years old. I would clean the old thermal compound between the CPU and the heat-sink, then apply new compound.

    Only do this if you feel comfortable doing this. Otherwise bring it to a professional.
     
  3. Digerati

    Digerati Major Geek Extraordinaire

    Unless the old thermal compound's cured bond has been broken, I see no need to replace it. TIM - thermal interface material does not get old and "go bad" if the cured bond remains in tact. A bad application of TIM typically causes temperatures to be consistently bad. If the bond is broken, then yes, the mating surfaces should be thoroughly cleaned and a fresh new layer of good TIM should be properly applied.

    I think we are seeing two different sets of sensors. Your core temps are consistently good - very good actually - with all the monitors, never exceeding 54°C. It seems to be the motherboard sensors that are reporting temps in the 70s.

    Note that your ASUS motherboard should have come with a hardware monitor - see the utilities disk or visit the board's download page. ASUS calls their monitor, PC Probe. Verify your temps with that, then stick with one real time monitor. I use Core Temp on all my systems.
     
  4. Death Zebra

    Death Zebra Private E-2

    It's 3 years and 4 months old (aside from the GPU which was installed in september 2009).

    I've been having serious trouble getting PC Probe to work but I've finally been able to verify the temperatures both when it's running "normal" and "hot".
     
  5. Digerati

    Digerati Major Geek Extraordinaire

    And what were they?
     
  6. Death Zebra

    Death Zebra Private E-2

    PC Probe agrees with HWMonitor (specifically, its THRM reading) and the BIOS. When it's running "hot" it shows a temperature of 71C and when it's running "normal" it's in the low 30s.
     
  7. Digerati

    Digerati Major Geek Extraordinaire

    I get nervous when CPU temps hit 60°C so for me, 71°C is unacceptable. If the cured bond of the TIM has been broken, then you need to apply a new fresh layer of TIM. Note the bond can be broken by twisting too hard on the heatsink (often to see if it is tight) or rough handling during transport.

    With the side panel open, blast a desk fan in there to see if that helps. If it does, you may need to consider adding a new, or larger case fans for better flow through the case.
     

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