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After Re-applying thermal paste, Temp skyrocketed

  • CPUs
  • Heat
  • Thermal Compound
Last response: in CPUs
August 10, 2009 3:51:42 AM


CPU=e8400 core 2 duo(not overclocked)
Heat Sink=stock
thermal paste=Dynex silver compound

I decided to clean my cpu's heat sink. Before putting it back on, I scraped off the old thermal paste, which came pre-applied, with a plastic card. I cleaned off the cpu heatspreader and the heat sink plate with 91% isopropyl and coffee filters(heard they leave very little debris). I have made 2 attempts to reapply new thermal paste(Dynex), and the temperature of my CPU is still far higher than it ever was. Temperatures are:

Idle=55-65 C minimum
Spikes up to 80 C when loading a graphic intensive game
before removing the heat sink to clean it, CPU temp rarely exceeded 55 C even under load.

Attempt 1: Put a dab on the center of the CPU heatspreader, and spread it out evenly with a card until entire surface was covered.

Attempt 2: Put a rice grain-sized dab on center of CPU heatspreader, but this time just let the Heat Sink spread it out as I affixed it.

Temperatures were equally high after each attempt.

My theories to explain the temperature increase:

1. The paste simply needs time to work in.
-But it has been 2 hours with no improvement whatsoever

2. I caused considerable microscopic damage to the heat sink plate when I scraped off the old paste, which caused too many heat-retaining pits too form.
-But even if the surface of the heat sink was made more irregular, couldn't the paste just seep into all the new pits anyway?

3. The thermal paste just sucks
-Couldn't imagine it sucking more than the pre-applied stuff

4. The Heat sink isn't attached firmly enough
-I got it in there really tightly. Even rotated it 1-2 degrees to supposedly remove air bubbles in the paste.

Cleaning this heat sink out has caused more harm than good! Any insights?

More about : applying thermal paste temp skyrocketed

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August 10, 2009 4:29:08 AM

1 yes but it only changes a few degrees
2 no unless you used a brillo pad or some such
-you want as little paste as possible to do the job- metal conducts better than paste
3 doubt it but could be bad batch as5 is cheap, easy to find, and works great
-intel's pre applied paste is an excellent product
4 if the pins are in and not damaged you are fine

Alcohol and coffee filters is good. Make sure the heatsink is all the way down ie not caught on a resistor or choke holding up the corner. Here are directions for applying paste.
August 11, 2009 12:00:25 AM

solved. embarrassing though. I was re-installing the heatsink each time while the motherboard was still in the case. I pressed as hard as I could on the plastic pins without breaking the MB, and figured that would be enough. The heatsink wouldn't move when i jostled it.

After taking the motherboard out of the case, I could see that one of the pins was not fully in place, creating a slight gap between the CPU heatspreader and the Heat sink plate. Only while holding the back of the MB while putting enormous pressure on the pin, was I able to get it in all the way.

ADVICE:D ont be stupid like me, always take out the motherboard to install a heatsink!
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August 11, 2009 2:39:31 AM

That happened to my cousin. He got reads of 100C. With that exact CPU, now that I think about it.
August 11, 2009 4:25:12 AM

no worries glad we could help
January 29, 2013 10:22:39 PM

that's a kind of a horror story because removing the heat sink is as far as I feel safe to go, I have never been able to remove a motherboard in a laptop, though I tried once. By the way my temps are very similar to the bad ones here, i.e. over 50° in idle and 70-100 + restart in load, so I'm going to re-apply thermal paste as soon as I get all components. But I hope I won't have to take apart everything. Still it's good to know what to look out for.