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CPU Temp Rising and Sinking Rapidly (on / off load)

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October 13, 2011 7:40:29 AM

Hi,

I'm running a
- Core i7 2600K @ std clock speed on an
- MSI Z68A-GD33 (G3) board using a
- Skythe Katana 3 CPU fan in an
- Enermax Chakra big tower (25cm fan on the side).

So far so good, everything works fine, the thing is pretty quite and fast as ****.

I've set the CPU fan to run at 37.5% unless the temperature hits 50 degrees Celcius at which point it picks up speed. This seems to work fine as well.

Idling, the CPU reports about 37 degrees (distributed evenly among the cores accoring to realtemp).

On starting Prime95, it takes about 2 seconds for the temp to hit 58 - 60 degrees at which it stays until i stop it. On ending Prime, it takes about 2 seconds for it to drop to 37 degrees again.

I've read about other users having the same, and most people say something like "as long as the temps are ok, it can be ignored" or that the thermal paste should be reapplied, etc. Apparantly, it's also normal using water cooling (which I am not using... ).

Can anyone give me feedback on this - is it normal? Should I do something about it? (If so, what?)

/wave
JJ
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October 13, 2011 9:01:56 AM

Its perfectly normal....

PRIME95 puts all CPU cores under 100% load......This OBVIOUSLY is going to cause a rise in temperatures.....


Your CPU is going from an idle load (low temps) to a full load (high temps)....When you end PRIME95 your CPU is going to back to idle and your CPU cooler is doing its job. The more load on the CPU, the hotter it gets.

Generally the faster a CPU cooler can return load temps down to idle temps, the better the CPU cooler is.

Nothing is needed to be done. Your CPU and Cooler are both doing exactly what they should be doing....
October 13, 2011 9:13:29 AM

Well, I understand that a CPU in use is going to cause more heat, and that a CPU in idle less.

What I am not quite sure I can believe, is that these changes of 23 degrees C happen within mere seconds - especially the cooling bit. It just seems odd...

And yeah, I guess as long as no extremes are reached, I should ignore it. If it was a bit more of a gradual slope (instead of the binary "cpu full, fan full, temp full" or "cpu idle, fan idle, temp idle") I could optimize my fan throttling a bit more...

Thanks though :) 
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October 13, 2011 9:16:22 AM

Just set your fan to auto. It will do its own thing then - cooling as necessary and speeding up when required.

Imagine yourself standing in a shower, and then jumping into a bath of ice and cold water.......how long do you think it will take for you to feel the cold? Then jump back into the warm shower, how long will it take to warm up? Point being your CPU is jumping between extreme's - its going to heat up QUICK when it suddenly gets dumped with a 100% load using all its resources.

Cooling down afterwards is totally dependant on the cooler, either way, the quicker, the better.
October 13, 2011 9:27:13 AM

Sounds normal to me, you have nothing to worry about. 58-60 C is a good temp for Prime95.

My i7 950 hits 65 C at 3.6 Ghz
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October 13, 2011 10:18:22 AM

Well? Do you have an AC on in the room where the rig is?
That why they make HSF with a lot of research not just slice up aluminum with a copper screw under it.
It's meant to drop the temps ASAP, if it hung around at those high temps after a doze of Prime95, it wouldn't be much of a cooler would it?
!