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Old April 20, 2009, 10:35 PM
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Originally Posted by sswilson View Post
Here's what I've come up with WRT my impression of the IC7 peaking at max temp vrs MX2 staying fairly consistent.....

The graph at the top is the IC7 and the one on the bottom is the MX2. Don't get caught up with the actual posted temps, as these are coretemp temps, and I'm not even sure if these MX2 readings are the actual ones from the run that ended up being recorded... I only know from the time frame that they are MX2.

If you look at the temps on the top graph (IC7) you'll see that the lower "load" temp is fairly consistant, while the max "load" temps are temporary spikes rather than the norm.

Looking at the temps in the lower graph (MX2) you'll see that the trend is just the opposite. On this graph the higher "load" temp (max) is fairly consistant, while the temporary spikes tend towards the lower temps.

Based on this, I'm pretty sure that the IC7 "average" temps over the whole 1 hour time frame would be at least 1c better (probably more) than the max/min peak readings would indicate.

Does that make sense folks or am I looking at this the wrong way?
One possibility

Just a thought from more of a mechanical point of view. I believe the electronics are pretty solid but the problem may be one of resolution.

Where I see fluctuations in readings on a synthetic die with metered power supplies the fluctuation mostly occurs in the ambient air reading which affects the power source temp.

I usually place multiple thermocouples for ambient temps and average them and when I take a reading I stand a few feet away. Thermocouples are so sensitive that just standing near them a couple of feet away they will pick up your body heat and the warmed up air you breathe and cause temp fluctuations of as much as a couple of degrees C, even 5 feet away normal air currents will move the reading up and down 1/2 a degree.

This in turn affects the source reading - if the sink is warmer or colder the source heat will be warmer or colder. Whatever happens upstream affects the down stream heat flow and when the downstream changes it affects the upstream heat flow.

To me it looks like the electronics are picking up the ambient fluctuations indirectly and/or directly from downstream heat flow changes

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