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Lapping a 775 down to copper??

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brentcatoe

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Aug 16, 2005
I got the strange notion the other day to lap my CPU. I got it really shinny and flat but noticed that it had gone down to what looked like copper around the edges. Does anyone think I would get better heat transfer to my heatsink if I lapped it down to all copper?
 
Ssetre said:
It would make very little to no difference at all. As long as its flat and smooth. Thats the important part.
Click to expand...
well, if he lapped it and got to the copper at the edges first, that means that its slightly convex, which may be hindering heat transfer

i'd say grab the 400 grit and lap away down to the raw copper, and then step your way up to 600, 1000, etc. for a mirror finish on it

and little to no difference? my CPU temps dropped 4ºC after I lapped the IHS on my 3.0E :attn:
 
If you got it to the copper WHILE keeping it perfectly flat then I would expect a 2-3 degree drop in temps. Just make sure you take your time. Perfection takes much time.

PEACE
 
I have lapped CPU's before and have never got a mirror finish, although I have measured the thickness across the cpu and it is as flat as I think it can get. How do you get a nice mirror finish on it. Before I have just used 400,800,and 1,000 grit. I think I am using too much pressure though when I am doing it, how hard are you supposed to press down on it?
 
I am using 3M imperial wet or dry sandpaper and I am using a little spray bottle to spray water onto the sandpaper. If I had my digital camera I would pull it and take a picture of it. I am getting my new Big Typhoon heatsink tomorrow and I am planning on re-lapping it and taking some pictures before I put it on.
 
with silicon carbide paper and wet sanding, i can never seem to get a mirror finish either, so i usually just dry sand the entire time
 
I myself doubt that wet sanding would bring about enough friction to make any difference... in general, you usually wet sand surfaces that are soft and easily scratched *like plastic*.
 
I used 800 grit and followed up with 2k grit paper.

IMG_1914.jpg


IMG_1916.jpg


IMG_1923.jpg
 
Once again its paint. Thats how they get the letters in there. Im suprised you didnt know that. At best its been laqured on. Either way its paint. Its designed to keep the top from rusting to ****. It does a good job at that and thats just about it.
 
Sentential said:
Once again its paint. Thats how they get the letters in there. Im suprised you didnt know that. At best its been laqured on. Either way its paint. Its designed to keep the top from rusting to ****. It does a good job at that and thats just about it.
Click to expand...


Not to say you are wrong Sen, but do you have a link to where it says it's paint that's applied? I haven't messed with any pressies yet and I didn't lap the IHS on my northies, but I did lap the cap on an old P3S tully I had and it's IHS definitely had an electroplated coating on it. Whether is was nickel or not I couldn't tell you, but it definitely wasn't paint.
 
i did my 775 3.2 down to copper and it dropped 4 deg on water cooling...

i belive my chip was extremely uneven though...

started at 320 grit- 600 - 1000 for about a hour - 1200 for half a hour -1800 then used a coffee filter and electrical cleaner spray to get a clear finish...

i did both water blocks to 1800 as well at the same time DD tdx and DD maze ati...
finishing up with a small blob of AS5 centered on the chip "wich does work best for me" and a thin layer of AS ceramic on the vid card...

worked for me, i'm happy :)
 
Ummm hate to break it to you guys, but IHS are meant to be domed these days. There is a deliberate spring action in them. When a HSF is mounted with correct force it's meant to ping down the middle to make a good clamping interface with the core. If you lap it, the middle either doesn't ping and you've got bad contact with a void under the heatspreader or it does and you've got bad contact with a void between the spreader and sink.
 
most of us have had temp drops after lapping the IHS though... i dont think that any P4 mounting mechanisim exerts enough force to compress the IHS that much to "ping" it
 
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