i7-2920XM very big temperature difference between cores

[ClevoFan1]

Hello,

I am owner of i7-2920XM. It's currently set to run at 3.4 GHz. I have a big problem with it. If i repaste and reseat hetsink then temperatures under load are about 83-85C on 3800 MHz maximum on each core. After 1-2 months temperatures will differ much on Core 2 and Core 3. When Core0 has 83 then Core 2 has 97C or even 100C!). It only happens after a 1-2 months so the time matters. Im tired of constant repasting the CPU.

I replaced CPU fan (upgraded it) to high speed one. Also bought new thermal paste but it's still same, fine for 1-2 months then gets very hot. What can cause this? Heatsink defect or it's just CPU defect (I doubt it)?

I presume that it can be a bad heatsink. I can do the lapping, I have a machine to do this. I wonder if is there a way to check if heatsink is good or askew?

It's not important but laptop is Alienware M18xR1 with thriple-pipe CPU heatsink (XM) and highest speed 11.4 CFM Fan (XM)

Regards and waiting for your reply

 

[ATMINSIDE]

What paste are you using?

 

[ClevoFan1]

GC Gelid Extreme and Zalman STG-2

 

[ATMINSIDE]

Unless I'm mistaken both of those pastes are fairly thin, correct?

 

[ClevoFan1]

Yes, GC Gelid Extreme is even easier to apply.

 

[ATMINSIDE]

I suggest getting a tube of Tuniq TX3, it's incredibly thick.
See if it lasts longer than the 1-2 months you're getting right now.

 

[ClevoFan1]

Hey,

I also tested some other paste that name I don't remember. All of them are lasting similarily and Im using 1 year old Zalman STG-2 on GPUs and they are very cool so it's not thermal paste issue.

Regards

EDIT::
Corrected some spelling mistakes.

 

[ATMINSIDE]

When you apply the paste though, how thick is it?
Does it somewhat spread out, almost semi-liquid like? Or does it hold shape until you put the heatsink on?

 

[ClevoFan1]

Hey,

It's huh, dunno how to spell it. It's not spreading out by itself. I need to spread it using included spatula so I will have thin layer on whole heatsink. Im trying to make pretty thin layer. Then I put the heatsink and that's all. It holds the shape, does not spread out like water.

 

[ClevoFan1]

I have a idea. If heatsink is not 100% flat then when moving the laptop thermal paste can move a bit to the "holes" in the heatsink so it will leave some parts of the CPU uncooled that's why core 2 and core 3 has higher temps. It's always core 2 and core 3 so it can be heatsink defect above these cores. What if I do the lapping? I also have my old 2-pipe heatsink, I can try mounting it for 1-2 months and lowering clock.



What do you think?

 

[RGE]

I would try a thicker thermal paste and apply a little more of it as Atminside suggested. Thermal paste between an IHS and heatsink on desktop isnt very susceptible to pump out. But on laptop where the paste sits on the die, there is much greater chance of tim pump out or separation. All of us that delided our desktop cpus and placed thermal paste directly on die have seen the same thing as you see, ie increasing temps and increasing temp spread over few weeks to months, if we used certain pastes not well suited for direct die application. Intel uses a thicker consistency tim and applies a thicker tim bondline (larger amount of tim) just to avoid direct die pump out.

Here is quote from an article describing the two:

The two main causes of increase in thermal resistance of a grease layer are grease pump-out and grease dry-out. The powering up or powering down of the device causes a relative motion between the die and the heat spreader (in-plane and out-of-plane), which tends to squeeze the thermal grease out of the interface gap. This phenomenon is referred to as “pump-out” and results in increased thermal resistance due to loss of grease material from the interface [1, 3].

Grease “dry-out” occurs due to the separation of the filler from the polymer matrix at elevated temperatures. The polymer matrix tends to flow out of the interface preferentially and results in ‘drying-out’ of the thermal grease. This results in increased in-situ thermal resistance of the material [1]. Exposure to high humidity levels has also been shown to induce changes in the thermal resistance of a grease layer, primarily an effect of the filler and resin system employed and their response to high levels of moisture.

http://www.electronics-cooling.com/2007/11/reliability-testing-of-thermal-greases/

 

[ClevoFan1]

Hey,

Okay I can try.

 

[ATMINSIDE]

Also don't spread it out, the heatsink will do the spreading for you.
Put on a drop between the size of a rice grain and a small pea, let the heatsink spread it.

 

[ClevoFan1]

Hey,

I always put a thermal paste like this size but maybe I shouldn't use spatula. I'll try to make it like you said and I'll update this thread after some time.

Regards

 

[Cpt_Chemtrail]

You could put a 1/4 inch of thermal paste on there and it wouldn't make any difference. I have heat problems a lot in the PAST....Not anymore since I upgraded to Corsair water cooling solutions like the H80i and H100i coolers. I guarantee you will never have problems with heat ever again. I wasted money on air cooling for too long, just a waste of money. Make sure you buy after market "silent fans" to replace the stock ones, if noise is an issue.........Just my two cents anyways...

 

[ATMINSIDE]

You could put a 1/4 inch of thermal paste on there and it wouldn't make any difference. I have heat problems a lot in the PAST....Not anymore since I upgraded to Corsair water cooling solutions like the H80i and H100i coolers. I guarantee you will never have problems with heat ever again. I wasted money on air cooling for too long, just a waste of money. Make sure you buy after market "silent fans" to replace the stock ones, if noise is an issue.........Just my two cents anyways...

Good luck fitting an aftermarket water cooler into a laptop

 

[wingman99]

I use the Grain of rice or a little smaller, I have gone with no TIM just for fun it worked ok. I think the thinner the TIM is the better it is, less of a barrier.

 

[ATMINSIDE]

I use the Grain of rice or a little smaller, I have gone with no TIM just for fun it worked ok. I think the thinner the TIM is the better it is, less of a barrier.

Depends on the cooler and the CPU in question.
In this case, less is not necessarily better because you're talking a flat heatsink direct to die.

 

[Silver_Pharaoh]

Hey,

I always put a thermal paste like this size but maybe I shouldn't use spatula. I'll try to make it like you said and I'll update this thread after some time.

Regards

Might be possible that by spreading out the TIM, you are introducing air between the heatsink and die.
Hopefully the thicker TIM works for you. Reapplying paste every month truly sucks!

 

[Mr.Scott]

All bare dies should be spread, period. Any part of a bare die that does not have TIM on it is a hotspot. Hotspots can kill.
Anyhow, I agree, thicker TIM and thicker application.