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Minimum 4C Temp Difference on Core #2

B

bore_u2_death

Limp Gawd
Joined
Sep 9, 2010
Messages
357
Hi Everyone. I installed a CM Hyper 212 Plus on my processor today. I used Arctic Silver 5 which I purchased around 6 years ago. It was stored horizontally. I used a plastic glove to smooth the AS5 across the entire surface of the contact patch, using the size of a small pea. In Speedfan using stock settings I have a 4C difference in temp. from core 2 (third core) all the time. Is this normal or is it an issue? How can it be corrected if it is in fact an issue?

And on a side note, the surface of my Hyper212+ is not perfectly flat. It has direct contact heatpipes. Like this:

http://www.gtec.my/product/coolermaster/cooler/hyper212plus/hyper212plus.jpg

Will grinding the surface increase cooling performance noticeably?

Thank you

UPDATE: My questions have been addressed thoroughly. I was alarmed at the constant temp. difference, but seeing as the CPU main temp. idles at 23C, no worries. I will grind away the surface in the near future.

Thanks again :)
 
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Differences in temperature between cores on the same CPU are normal. They can be caused by some cores performing better than others (less current leakage) or achieving better contact w/the integrated heatspreader.

AS5 is not really appropriate for a direct contact heatsink; as you've noticed, it's too thin to fill the gaps between the pipes. You will probably see slightly better temps with a thicker paste such as Shin-Etsu 751/7783D or or Tuniq TX-3

Be careful w/that grinder - the heatpipes aren't particularly thick. Though it won't be terribly expensive to replace if you do kill it.
 
I don't believe you are supposed to fill the gaps on a direct contact heat sink. From some reviews I've read, the spaces basically will hold any excess paste which is pushed to the left or right of the heat pipe, but that it doesn't positively impact temps.

The majority of what I've seen is the same method the OP used to apply.
 
thefreeaccount said:
I'll admit that I've never seen any benchmarks, but it seems obvious to me that thermal compound will conduct heat much better than air in those gaps. That's what benchmarkreviews recommends:

http://benchmarkreviews.com/index.p...sk=view&id=170&Itemid=38&limit=1&limitstart=5
Click to expand...
The gaps do not provide any significant contribution to the heat transfer. It doesn't matter if they are filled with air. The only benefit to filling the gaps that I can see would be to ensure that the rest of the thermal paste is spread across the surface of the heatsink base rather than being pushed into the gaps when the heatsink is installed.
 
The gaps do not provide any significant contribution to the heat transfer.
Click to expand...
Cite? That's hard for me to believe...even the slight improvement in contact provided by lapping an already relatively flat surface can reduce temps by a couple of degrees. Small differences in mounting orientation and pressure applied can also result in a couple C difference +/-.

As far as contact is concerned - little things do count. Which makes sense if the heatsink is operating at/near the limit of thermal transfer.
 
thefreeaccount said:
Cite? That's hard for me to believe...even the slight improvement in contact provided by lapping an already relatively flat surface can reduce temps by a couple of degrees. Small differences in mounting orientation and pressure applied can also result in a couple C difference +/-.

As far as contact is concerned - little things do count. Which makes sense if the heatsink is operating at/near the limit of thermal transfer.
Click to expand...
Lapping an already flat surface never has a significant effect, though in many situations a surface that 'appears' flat is in actuality quite uneven. Differences in mounting orientation and pressure result in temperature differences because they can have a large effect on the contact between the CPU and the heatsink base, and obviously changing the orientation of a heatsink within the case affects the way in which it interacts with the case airflow.

Filling in the tiny gaps between heatpipes on an HDT cooler won't do much, since the surface area of the filled-in gaps is extremely small and the amount of thermal paste between that surface and the surface of the CPU heatspreader is much larger than the amount between the CPU and the flat base of the heatsink. The increased amount of thermal paste required to fill in the gap will provide a great deal more thermal resistance than the thin layer between the base and the heatspreader.
 
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