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what is your heat sink temp?

silverblack

silverblack

macrumors 68030
Original poster
Nov 27, 2007
2,680
840
What is your heat sink temp when the cpu is running hot, like 90+ degree C?

I recently performed the excess thermal compound removal procedure. Now I am worried that my cpu and heat sink are not in 100% contact, due to the very small amount of paste applied.

My heat sink sits at around 50C under normal load (cpu temp ~ 60). But at high load, cpu up at 90+ C, my heat sink is still at around 50-60C. Is this normal?
 
O

Olvenskol

macrumors member
Feb 20, 2008
81
0
FWIW, my unmodified MBA reports a similar difference between a hot CPU and the heat sink when I push it. 85-90 CPU, 55-60 heat sink. So I would guess that is normal, since the machine seems to behave correctly when it gets pushed.

I haven't opened mine up... does the heat sink have an actual sensor on it? Or is it being estimated from some nearby sensor. And if it does have a sensor, is it near the contact point or near an edge. There should be a pretty big difference across the surface of the heat sink.
 
silverblack

silverblack

macrumors 68030
Original poster
Nov 27, 2007
2,680
840
Olvenskol said:
FWIW, my unmodified MBA reports a similar difference between a hot CPU and the heat sink when I push it. 85-90 CPU, 55-60 heat sink. So I would guess that is normal, since the machine seems to behave correctly when it gets pushed.

I haven't opened mine up... does the heat sink have an actual sensor on it? Or is it being estimated from some nearby sensor. And if it does have a sensor, is it near the contact point or near an edge. There should be a pretty big difference across the surface of the heat sink.
Click to expand...

Thanks for the information. This makes me feel much better, and I won't have to re-open it to check.

By the way, there were not any wires or sensors attached onto the heatsink metal plate. So I also don't have any clue where exactly the heatsink temp is measured.
 
dahcheet

dahcheet

macrumors regular
Feb 7, 2008
221
0
Harrisburg, PA
Olvenskol said:
FWIW, my unmodified MBA reports a similar difference between a hot CPU and the heat sink when I push it. 85-90 CPU, 55-60 heat sink. So I would guess that is normal, since the machine seems to behave correctly when it gets pushed.
Click to expand...

That sounds about the same for my unmodified MBA.
 
hkq37

hkq37

macrumors newbie
Apr 26, 2008
13
0
Hong Kong
my temps after mod

Last night I opened up the MBA so I could re-apply heat sink paste to the CPU as described in the other thread "Be gone. Noisy Macbook Air!"... put it all back together and then ran Youtube vids for about 10 minutes.
I got 80-90C CPU and 55C heatsink, 6200RPM

So I turned it off, pulled it apart again. Then I noticed the heat sink paste wasn't even touching the heat sink!!!! The heat sink shiny metal pad was still shiny clean !!:p

So I re-adjusted it and applied a bit more paste.

Re-simulated my test and now its going ( after 45 minutes of Youtube now i.e. stable)
70C CPU, 56C heatsink 6200RPM ( NB.>same as is was 'out of the box' )

Conclusion
1) Re-applying heatsink paste didn't change much
2) The heatsink is poorly designed, it is not designed such that it pushes against the CPU.

Looking at your results I wonder how good your contacts are and even if it is poor, there isn't really much you can do about it !
 
Scott6666

Scott6666

macrumors 65816
Feb 2, 2008
1,487
936
Yes!

hkq37 said:
The heatsink is poorly designed, it is not designed such that is pushes against the CPU.

Looking at your results I wonder how good your contacts are and even if it is poor, there isn't really much you can do about it !
Click to expand...

Couldn't agree more. The heatsink IS poorly designed, particularly to take into account natural variations in a manufacturing process.

A $1 part screwing up a $1,800 piece of art. Disgraceful!!!!!!!!!! Some one engineer at Apple (and his boss) need to fired.
 
silverblack

silverblack

macrumors 68030
Original poster
Nov 27, 2007
2,680
840
hkq37 said:
Last night I opened up the MBA so I could re-apply heat sink paste to the CPU as described in the other thread "Be gone. Noisy Macbook Air!"... put it all back together and then ran Youtube vids for about 10 minutes.
I got 80-90C CPU and 55C heatsink, 6200RPM

Looking at your results I wonder how good your contacts are and even if it is poor, there isn't really much you can do about it !
Click to expand...

Thanks for pointing this out. I reopened my MBA to check, my cpu-heat sink contact was indeed very bad. I have reapplied more thermal compound. Now, my cpu's stayed below 70C even at high load. Much happier.
 
NC MacGuy

NC MacGuy

macrumors 603
Feb 9, 2005
6,233
0
The good side of the grass.
Agreed the heatsink may be an Achilles heal but with the design constraints of the area allowable for it, there's not much play to get a whole lot more there.

You'd need either more heat dispensing mass or area and it's just not available. Maybe next iteration they'll widen air circulating vents as they did in subsequent MBP releases to get more air through fan and over heat sink.

We shall see.
 
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