Aces High Bulletin Board
General Forums => Hardware and Software => Topic started by: Ruler2 on January 30, 2010, 11:15:35 AM
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Are there any advantages or disadvantages to lapping a CPU? Is it worth potentially killing it to make it smoother, or can extra thermal compnd do the equivalent?
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According to what I read, it is one of those "80/20" kinds of things... you gain maybe 20% benefit for around 80% more work.
From personal experience helping my Dad "grind" a reflecting mirror for an astronomical telescope, working by hand with fine grit abrasives is very, very, VERY boring!
If a heatsink has a nice mirror-smooth finish, it's good enough for me.
YMMV
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According to what I read, it is one of those "80/20" kinds of things... you gain maybe 20% benefit for around 80% more work.
From personal experience helping my Dad "grind" a reflecting mirror for an astronomical telescope, working by hand with fine grit abrasives is very, very, VERY boring!
If a heatsink has a nice mirror-smooth finish, it's good enough for me.
YMMV
Man I've been kind of wanting to try that for the last few years. I read where you can use the bottom of a bottle and polish it into a lens too. There's a guy who's name I can't recall this very second that gives the plans on how to make a 6 or 8 inch scope away and shows how you can make one for very little money. I always thought that might be an interesting project and having a big scope like that would be fantastic.
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I always thought you would lap the HS..not the cpu
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You can lap a cpu's heatsink but there is far more benefit (and risk) removing it to expose the cores. The last one i've done was on my amd X2 4400+ . It lowers the core temp almost 4 degrees under load ...at least thats what it did for me on water. I'm unsure about new cpu's thou
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This is one of those risk<reward situations. There's alot of info on Lapping here www.overclock.net . You're going to have to be the one to determine if the reward is worth the risk. Might I suggest trying it out on a test dummy first? Some old CPU or something.
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I first read about lapping in one of the reviews on newegg so I ordered a kit and tried it. I have never lapped the CPU itself but I have lapped the last four heatsinks I have used and the temperature does drop significantly (6-12C) and even more so if for the next three months you turn the computer OFF after use and allow it to return to room temperature. I used Arctic Silver 5 on a Blue Orb II and got a 8C drop that eventually became a 12C drop once it baked in.
Okay so after you do this to the heatsink even if you overclock the CPU stays within a temperature range it can tolerate and if you did the same thing to the CPU it would get cooler by maybe 3-5C but I dont see that as being worth the risk (if thats what you are asking).
Here is the kit I use:
http://www.easypckits.com/products/premiumlk/
It is a little more expensive than the other kits out there (as low as $6) but if you do 100 repetitions of each grade in two directions or 200 repetitions in a circular pattern for all grades the finish will be as smooth as the surface of a mirror. Make sure you read the directions and if your heatsink has a sharp edge on the edge of the surface area you should bevel it down or it will ruin your lapping kit. You will also want to set the glass surface on a towel on a firm stable surface near the sink (using a bowl of water will retain larger particles that you DO NOT want to get into the operation again) where you can get water directly from the tap or fill a water sprayer (what I do) and spray the glass before laying the paper on the glass and then spray the paper before using it and keep it wet and CLEAR (I ran it under the tap after every 20 repetitions).
The stricter you are to the process the better the results will be.
Since it involves water I recommend NOT doing this to your CPU.
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So is this just like basically sanding your CPU heatsink to get a smoother surface to create more contact?
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So is this just like basically sanding your CPU heatsink to get a smoother surface to create more contact?
Got it in one. The problem is there is so many things that could go wrong. If the surface isn't even, smooth, and level you basically screwed it up.
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I have "lapped" 7 or 8 processors. I do see a good difference in the temps. Problem is that you should also lap your heatsink too. I finish with 3000 grit (mirror fine) wet dry. I use a large 1/2 piece of glass and tape my sand papers to it, also use water and a drop or liquid dish soap for lubrication. Takes about 4 to 5 hours to do each.
TD
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Its just as easy to keep it right. The only way to screw it up really is to rock the heatsink while you are doing the lapping. The reason you dont want to do this to the cpu is obvious (broken pins or water damage). The larger the heatsink (bulkier) the easier it would be to get a rocking motion going which is BAD. While working on the Orb type heatsinks I took the fan off so the motor would not get water in it. I had to do the first one because I bought into one of the 'open box' sales that newegg had and the heatsink had a huge impact point on the mating surface and it took nearly 500 repetitions just to get that to a point where I could not see it. I have bought heatsinks that came 'stock' with the mating surface not at all level so this is not a bad trick to learn.
Even with TilDeath saying he has done it to CPUs and being able to afford a few mistakes... I wont do it.
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i wonder if a person couldn't take a old motherboard and cut the section out that holds the CPU. Install CPU, lock it in and use the old MB as a way to keep it flat. COuld allways take a little piece of wood and glue it on the back of the MB for a handle. Just an idea.
Years ago I fell hurt my shoulder at work, since I couldn't lift anything for a couple of weeks, I had a job in the shop for a few days lapping valve lifters for the new diesel rebuild they were doing.Didn't take long for that job to get old
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Gentlemen I paint boats for a living. Now I'm guessing you are wondering what this has to do with lapping a cpu or a heat sink. Our finish primer is wet sanded to 400 grit and if the boat is getting a clear job it is wet sanded to 600.
This requires medium pressure. Now I've done quite a few jobs where the clear is sanded and buffed. Starting with 1200 and ending with 2000 grit then a buffing compound. The 2000 requires a very light touch and keeping the work surface clean.
TD method of using plate glass is a perfect idea. I would like to add let the paper do the work. You just want to maintain even pressure. Do not force an imperfection out, you will just add more. As for buffing the cpu/heatsink...
Jewelers Rouge Polishing Compound. It is a bit messy but it does a fine job.
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Are there any advantages or disadvantages to lapping a CPU? Is it worth potentially killing it to make it smoother, or can extra thermal compnd do the equivalent?
I've never lapped a CPU or heatsink but don't just add thermal compound. Too much will add heat just the same as too little. As long as there's enough to fill any imperfctions that's all you need.
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I've never lapped a CPU or heatsink but don't just add thermal compound. Too much will add heat just the same as too little. As long as there's enough to fill any imperfctions that's all you need.
X2 gently slide CPU/Heatsink on sandpaper in a line do this for 10 times turn the CPU/Heatsink 1/4 turn 10 more repeat you will visually see when you need the go to the next grit up. When done you will use a very small amount of TC (1/3 the size of a pea)
TD