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E4300 - Very fast temp change with loading

Discussion in 'Overclocking' started by Bob F, Mar 19, 2007.

  1. Bob F

    Bob F Guest

    In experimenting with overclocking a new system, I've noticed that
    the CPU temperature displayed varies very quickly with load. Running
    orthos gets the temp (displayed by PC Probe II) up to 129F within
    a few minutes. Stopping orthos results in the temp dropping within
    seconds to less than 100F. This suggests to me that there is poor
    coupling between the heatsink and the processor, or internally within
    the processor. I tried removing the origional heatsink "paste" from the
    heatsink and processor and replacing it with some white dow corning
    silicone HS paste, with no improvement.

    It seems to me that the temp should vary much slower, as the heatsink
    gets hotter or cooler. Can a different grade of HS paste make a big
    difference in this, or am I interpreting the data wrong?

    Bob F


    Asus P5LD2
    Intel E4300 - w/HS/fan from QX6700 Extreme Quad core
    currently testing at 2.88 G OC
    Crucial ValueSelect 2x1G DDR2-667
    eVGA 7600GT Video
    Maddog 16X DVD +-RW
    WunXP Pro
     
    Bob F, Mar 19, 2007
    #1
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  2. Bob F

    Phil Weldon Guest

    'Bob F' wrote, in part:
    | In experimenting with overclocking a new system, I've noticed that
    | the CPU temperature displayed varies very quickly with load. Running
    | orthos gets the temp (displayed by PC Probe II) up to 129F within
    | a few minutes. Stopping orthos results in the temp dropping within
    | seconds to less than 100F. This suggests to me that there is poor
    | coupling between the heatsink and the processor, or internally within
    | the processor.
    _____

    What you see is completely normal. The temperature measurement for Intel
    CPUs comes from an on-CPU-die thermal diode. That temperature measurement
    reacts immediately to increased current consumption on the CPU die. There
    is a thermal resistance between the CPU die and the heat spreader; and an
    additional thermal resistance between the heat spreader and the heat sink;
    and an additional thermal resistance between the heatsink surface in contact
    and the heat spreader; and an additional thermal resistance within the
    heatsink; and additional thermal resistance between the heatsink and the
    cooling fluid (air or water.)

    The heat storage capacity of all of these elements before the cooling fluid
    is very low - not nearly enough to slow the temperature rise significantly.
    You may call that 'poor coupling' between the heatsink and the processor if
    you wish, but that's the natural world. The temperatures you report are
    pretty meaningless if you don't have the temperature of the cooling fluid
    entering the heatsink. The interfaces between the CPU die and the heatsink
    contact surface are only part of the total thermal resistance. If the CPU
    is only issuing halt instructions, the power consumption is only a few
    watts. In that case, the CPU temperature should only be a few degrees C
    above the temperature of the cooling fluid entering the heatsink. The 43.5
    C temperature you report at idle indicates the CPU is not issuing halt
    instructions, but just running in an idle loop (unless the cooling fluid
    temperature is ~ 40 C.) The 60 C temperature you report under load (if
    'orthos' is a processor stress test) is probably normal for a plain vanilla
    heatsink/fan and an Intel E4300 overclocked to 2.88 MHz.

    The important factor in judging the cooling solution is the CPU temperature
    compared with the cooling fluid temperature, NOT how quickly the CPU
    temperature changes.

    Thermal paste or thermal grease products all have very similar performance -
    even butter works well as a thermal grease ( other than the fact it leaks
    and goes rancid.) The highly hyped 'Arctic Silver' is only marginally
    better than zinc oxide sunblock. More important than the brand you use is
    how the thermal compound is applied, and how flat, smooth, and parallel the
    surfaces are.

    Phil Weldon



    I tried removing the origional heatsink "paste" from the
    | heatsink and processor and replacing it with some white dow corning
    | silicone HS paste, with no improvement.
    |
    | It seems to me that the temp should vary much slower, as the heatsink
    | gets hotter or cooler. Can a different grade of HS paste make a big
    | difference in this, or am I interpreting the data wrong?
    |
    | Bob F
    |
    |
    | Asus P5LD2
    | Intel E4300 - w/HS/fan from QX6700 Extreme Quad core
    | currently testing at 2.88 G OC
    | Crucial ValueSelect 2x1G DDR2-667
    | eVGA 7600GT Video
    | Maddog 16X DVD +-RW
    | WunXP Pro
    |
    |
     
    Phil Weldon, Mar 19, 2007
    #2
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  3. Bob F

    kony Guest

    If you had an "ideal" interface where the CPU was somehow
    embedded within the heatsink, you would be right (or closer
    to that at least), but the die is very small and coupling to
    the far larger heatsink is inherantly imperfect with a
    properly installed heatsink, let alone one improperly
    installed.

    The better your HS paste is, the smaller the difference up
    to a point, but you may already be at that point, or close
    eough that further effort has too diminishing a return. The
    key is not what the change is nor how fast, but whether the
    CPU remains cool enough to be stable and have acceptible
    lifespan when running at full load for an extended period of
    time. 129F is about 54C (we usually note CPU temps in
    Celcuis not Fahrenheit) which is cool enough.
     
    kony, Mar 19, 2007
    #3
  4. Bob F

    Ed Medlin Guest

    Your results are perfectly normal with a stock hs/fan. You are well within
    the operating temperature range of your processor. Please note that we
    normally use Celsius (I kind of always just think in C when relating to
    processor temps) instead of F. Your temps at the high end are low 50s C and
    are just fine as long as everything is stable. You might be able to bring
    the load temps down some with an aftermarket hs/fan if you want to spend a
    few extra bucks. I see no need to do so unless you want to try and go a bit
    higher with your OC. Another benefit is that many aftermarket soulutions are
    quieter because of their use of larger and lower rpm fans. In my experience
    Phil is absolutely correct as far as thermal compounds go. I normally use
    the cheap stuff from Radio Shack. My local computer shop gives me a tube of
    Artic Silver about everytime I buy anything there, so I use it because it is
    free....:). I see almost no difference between it and the cheap stuff.


    Ed
     
    Ed Medlin, Mar 19, 2007
    #4
  5. Bob F

    Bob F Guest

    Thank you Phil, kony, and Ed. It would seem that what I am
    seeing is probably mostly accounted for by the thermal resistance
    within the chip, since the temp settles very quickly to what I guess
    is the heatsink temp when unloading the processor.

    Bob
     
    Bob F, Mar 20, 2007
    #5
  6. You are probably also seeing the effects of the active processor multiplier
    and voltage management ramping up the CPU's performance level.

    While in an idle state, your processor should be running at reduced
    clockspeed and core voltage. As soon as you load it up, it should pretty
    much instantly revert to full speed/full voltage operation, with a
    corresponding increase in heat output.
    --


    Richard Hopkins
    Cardiff, Wales, United Kingdom
    (replace nospam with pipex in reply address)
     
    Richard Hopkins, Mar 24, 2007
    #6
  7. Bob F

    jaysmay

    Joined:
    May 27, 2008
    Messages:
    1
    Likes Received:
    0
    Also notice extremely fast temp shift

    Hey there,

    I found this post via google and the above mentioned heat issue is EXACTLY what I am getting.

    I have an E6850 which runs idle at about 40 C according to speedfan.
    It is not overclocked.

    I got worried from a beeping sound today when doing a huge excel 2007 calculation. Both Cores were 100% stressed for a period of a few minutes and the temperate rose to 80 C!

    I tried later playing some Crysis and noticed it jumped to 75C in that game.

    As soon as the load was removed the temperature dropped right back to 40C. I mean really within seconds.

    Could this be related to not having installed the cooler (Scythe CPU Cooler Mugen (Infinity) Copper) properly? Or some other connection issues/wrong coolingpaste?

    Some extra info:
    GFX: I run a 8800gt card with Arctic VGA Koeler Accelero S1 Copper
    Case: Antec Sonata III, 500 Watt
    Fans: 1 x case fan from sonata, 1x extra Coolink Fan Swif Retail 120 Mm (installed to pull air past harddrives.

    Thanx,
    Jasper
     
    jaysmay, May 27, 2008
    #7
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