Re-applying thermal paste made temp. soar

Intel Core 2 duo e8400 dual core process...
August 9, 2009 at 21:05:40
Specs: Windows Vista 64 bit

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 die 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 die, 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 die, 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?

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August 9, 2009 at 21:13:25
It is true that the thermal paste takes a while to "work in", in some cases up to a week or more. But this will only drop the temps 4 degrees (at best).

Where did you get the paste from and is it new? Sometimes old paste can be worse than no paste at all.

Be sure to check your fan and heatsink to insure it isn't damaged or stuck in any way.

Last thing I can think of is that it is not attached firmly. Those heatsinks usually come with the plastic pins that you push in then rotate. I've seen these fail sometimes during the first install. Since you've played with it a few times, I wouldn't be surprised the pegs are worn or broken. You might try getting different mounting hardware, such as the screw/spring hardware used on many other heatsinks.

-Ryan Adams

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August 9, 2009 at 21:25:30
Since you know you gouged the Heat Sink removing the thermal Pad, try a new one.

Thermal Paste works on the basis of having a consistent film thickness across the joined surfaces. Pits, gouges, scratches, allow for uneven paste distribution and localized hot-spots where heat collects and intensifies at the irregularities in the Paste film and Aluminum heat sink..

You could try resurfacing the contact surface of the heat sink, but why bother a new heat sink is cheaper.

There is nothing to learn from someone who already agrees with you.

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August 9, 2009 at 21:26:58
It's spiking to 70 degrees Celsius as I write this.

Paste is new, from Best Buy.

Yea the heatsink has plastic pins. But i did affix it until moving the heatsink caused the Motherboard to move too. My next heatsink will definitely be a model that screws in, this plastic pin apparatus is a pain.

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Related Solutions

August 9, 2009 at 22:34:52
What are you using to check the cpu temperatures. The e8400 is known to have issues with faulty temperature sensors. Was the cpu temperature OK before you cleaned the heat sink ?

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August 10, 2009 at 05:07:43
I don't know why I'm seeing minus points for good answers?

1. you didn't post what your temps were prior to removing the heatsink.

2. you didn't state why it was necessary to remove the heatsink & reapply paste. Did you do it out of necessity or did you do it for the hell of it?

3. applying the paste like you''re buttering a slice of toast is NOT how it should done. Your "Attempt 1" was totally incorrect.

4. your "Attempt 2" was also incorrect. The paste should be applied in a thin line & it has to be properly oriented on the CPU. The line of paste MUST run in line with the cores, not perpendicular to them. Here's the proper instructions:

5. as stated by kx5m2g, the E8400 is known to have temp reporting issues so it's possible that there wass nothing wrong with your temps until you started messing with things.

6. temp readings should be taken from the BIOS, not least not until you've compared the two enough times to confirm the BIOS & software are in agreement.

7. remove the heatsink again, thoroughly clean the top of the CPU & bottom of the heatsink again, then reapply the paste again using the instructions in point 4 above.

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August 10, 2009 at 05:46:39
I'm just wondering why you removed the thermal pad in the first place and decided to put grease on it, unless you were replacing the stock heatsink with a better heatsink to achive better cooling overclocking the processor. Other then that there shouldn't have been any need to remove the thermal pad that came with the stock heatsink and put grease on it.

Iron Sharpens Iron.

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August 10, 2009 at 11:24:24
1) He said in the first post, temps didn't exceed 55 under load.

2) He said to clean the heatsink (though even I don't know why he needed to remove the heatsink to do this.

3/4) Good points, the OP should read that link.

5) It would seem unusual to have the temp sensors working accurately before, and then suddenly stop.

6/7) Also good points.

-Ryan Adams

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August 10, 2009 at 11:41:03

I am using Asus Pc Probe II to check temps. It came with the motherboard. CPU temperature was always in the low 40's celsius before, even with all the dust in the heatsink. Never exceeded 55 C under load.

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August 10, 2009 at 11:49:00
jam, I've given no one minus points. I'll try that method.

I've checked th BIOS temps 3 times. In the 70's each time and then gradually went down to 55-60, but no lower.

It was not necessary to remove heatsink to clean it. It just makes it easier, and It's what I've always done. This is the first system I've built that required thermal compound, and it just slipped my mind when I chose to remove it. A stupid mistake.

And, omfg, it's up to 85 C right now because windows defender started scanning.

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August 10, 2009 at 11:51:00
So it shot up to 85 C under load, and now has dropped down to 55 C. I never paid attention to load temps before this, but a 30 degrees Celsius disparity seems outrageous.

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August 10, 2009 at 12:03:23
Oh, and I meant CPU heatspreader,not CPU die.

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August 10, 2009 at 17:01:44
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:Dont be stupid like me, always take out the motherboard to install a heatsink!

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August 10, 2009 at 17:09:41
I'm glad you solved the problem-those push pins are a big pain. That's why I like a HS/F that screws into a backplate attached to the motherboard. I don't think you're supposed to put enormous pressure on the pin, though. The pins have to be turned to their p[roper position to reinstall correctly. When I've mesed that up in the past, I found that one of the plastic things was kind of messed up-I hope that's not the case for your HS/F.

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August 11, 2009 at 18:18:08
"ADVICE:Dont be stupid like me, always take out the motherboard to install a heatsink!"

Orrrrrrrrrr. Just don't mess with the heatsink unless you really need to.

Iron Sharpens Iron.

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