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Lapping - is it the way ?

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UnseenMenace

UnseenModerator
Joined
Apr 23, 2001
As most of you know, I am quite new to overclocking but have a knowledge that is ever expanding.. When researching my system, I was not aware of lapping a heatsink and thus built my system without doing so. Today however I built a PC for a friend and obtained the same heatsink as mine. I recalled a article on the front of overclockers.com which suggested that excessive lapping could actually hinder the heat transfer. I believe the article was concerning machining materials to precise measurements as well. I also read the Lapping Tips section and then attempted this task.
In the Lapping tips, it mentions rubbing grinding paste between the CPU and heatsink as an alternative to lapping.. so this is what I did to one heatsink and I lapped the other (lapped down to 600 paper).
To obtain a reasonably accurate result, I checked the room temp and fitted both FOP-32's to the same PC using the same clip and fan, while this is not scientific research as there may be manufacturing differences between the heatsinks, or between the amount of Artic Silver I used to assemble them each time..perhaps it suggests something.. but heres the temps reached after running the burn in on SI-Sandra for 30 mins

FOP32- Normal CPU @ 52 c | SYSTEM @ 27 c
(both FOP made same same temps at standard)

FOP32- Lapped CPU @ 48 c | SYSTEM @ 26 c

FOP32- Ground CPU @ 46 c | SYSTEM @ 26 c

I did it for myself out of interest, however I would be interested to know all your opinions
 
OP
UnseenMenace

UnseenMenace

UnseenModerator
Joined
Apr 23, 2001
I've just noticed what forum section this is placed, it was intended for the cooling section ( and this one is below it in the list ) so possibly slipped or wasnt paying attention... however and all I can do is apologize at this point to the person who will have to move it.. I should know better and believed I did.. but we all make mistakes
 

Betty

Senior Member
Joined
Jan 5, 2001
Location
Port Alberni, B.C., Canada
No worries...I'm sure it will be moved when Daniel~ sees it.
Interesting findings..I too have the fop 32 and am now off to the Lapping Tips to read about the grinding thingy you were talking about :)
 

Thelemac

Administratively Deficient
Joined
Mar 15, 2001
Since you're doing it anyway, it would be a good reference if you were to lap one with a higher grit, too. Such as 2000 /w ASII as the lube.

Otherwise it's very interesting to see your results.
 
OP
UnseenMenace

UnseenMenace

UnseenModerator
Joined
Apr 23, 2001
Thelemac (Jun 06, 2001 03:50 a.m.):
Since you're doing it anyway, it would be a good reference if you were to lap one with a higher grit, too. Such as 2000 /w ASII as the lube.

Otherwise it's very interesting to see your results.

The reason that I only lapped to a 600 paper was that the grinding paste was rated as being 600 so I felt that this created a fairly accurate result which was somthing I intended to do. The final lapping was not done with Artic Silver as I felt that this could dilute the paste as to be fair I would have to use it in that situation as well, considering the experiment was to test the techniques rather than the effects of a heat transfer compound, I believed in comparing like with like... However thanx for your views Thelemac and I will indeed lap one with a higher rate just to see the comparisons.. which will be posted here in the next day or so
 
OP
UnseenMenace

UnseenMenace

UnseenModerator
Joined
Apr 23, 2001
Ok I've now lapped the heatsink using 1500 grade paper (couldn't get 2000 grade today) and monitored room temperatures until they reached the same levels used in the previous test.

The heatsink was lapped using Artic Silver as the lube.. to ensure that there was no high or low spots the heatsink and CPU core was also brushed with engineers blue.. This complete process was completed on a mirror for a ideal flat surface (5 sheets of A4 paper were used to lap) These are the temps reached after running the burn in on SI-Sandra for 30 mins

FOP32- Lapped (1500 grade) CPU @ 47 c | SYSTEM @ 26 c

So there you have it a drop of 1c.. I am however unsure of if this can be compared to my previous results as it was done at a later date and things change such as dust in the air.. Perhaps lapping with 2000 grade paper will bring it down another 1c to match the grinding paste temps which today still read 1c lower than the lapped heatsink.

As previously stated.. perhaps not scientific.. but interesting all the same