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Is lapping, or sanding, your CPU and/or heatsink advisable in any situation?

I want to OC an Intel Core i7 5930k to 4.25 GHz using a Corsair H115i (because I'm scared of custom loops. Eeek!) and I would like to know if lapping your CPU and/or heatsink really works or if it is just a gimmick.

I first came across it on http://us.hardware.info and their tutorial seems very indepth and well put together; but I don't know if shaving off 7 measly degrees is really worth all of the hassle, and not to mention, risk.

Thanks all, Whitunga
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More about lapping sanding cpu heatsink advisable situation
  1. Best answer
    I would say no, especially on a nice new chip like that. I would not do such a thing without a milling machine and a grinder bit, as sanding it by hand is likely to leave a less than level surface.
  2. Lapping a CPU heat spreader voids it's warranty that is the biggest negative of all!

    I have to disagree with Robert Cook's statement above, however to his credit he did say he would not do it.

    A perfectly flat lapped surface can easily be achieved, If, you know what you are doing and lap on a true flat surface like a sheet of glass, that's what I use when I lap a surface.

    Whitunga, the link you provided shows exactly how it is done so you already have that resource, I advise you in the future not to choose a best answer with the first responder or you may miss some needed input as many here at Toms only respond to unanswered questions.
  3. What a splendid idea. My arctic freezer has got little riffles on the base just as the tutorial is critical of. I just practiced lapping a copper base heatsink on a mirror clamped to a desk which is just off level by a touch, & I stuck some card down and some card to some reasonably fine sandpaper and lapped for 30-45mins & then just got an old cpu to test it and I was pretty surprised by the results.

    The cpu stuck down so snugly that I could not lift it off with my fingers (using mx-2 thermal paste) and I had to prise it off with a ruler.

    The mirror polish was good enough that I could see my face at arms length but a bit blurry, better up close but still there were some fine lines. I tried the surface with the tip of my fingernail & found a rough spot and lapped it some more.

    The hardware store don't open 'til tomorrow but I'm going to lap my current cpu heatsink now and just get the riffles off and if I get good results leave it and if I need more fine grade sandpaper I can get it easy enough. 5c seems pretty good. I'm not going to lap the CPU because I'm reasonably sure the heatsink is the worse by far.
  4. Whitunga said:
    I want to OC an Intel Core i7 5930k to 4.25 GHz using a Corsair H115i (because I'm scared of custom loops. Eeek!) and I would like to know if lapping your CPU and/or heatsink really works or if it is just a gimmick.

    I first came across it on http://us.hardware.info and their tutorial seems very indepth and well put together; but I don't know if shaving off 7 measly degrees is really worth all of the hassle, and not to mention, risk.

    Thanks all, Whitunga


    The purpose of thermal paste is to smooth out the roughness. Therefore lapping will have only a small effect.
  5. Well I've been sanding for 2 hours last night and 2 hours this avo and polishing with a cotton doodad on the drill & I can't say that it has made any difference to me but I didn't lap the cpu & I noticed a couple of things anyway. The AMD stock heatsink already had quite a high polish on it and it is very flat on the base. When I rested the base of the Artic Freezer Extreme it looked a little bit convex in comparison.

    Sanding it down hasn't improved my thermals any that I can discern it seems to have made things worse rather than better. I couldn't tell you if the thing had been lapped or if it had merely been polished. I also cleared up the mess of my first installation where my CPU was idling at 0c while online typing here 'cos I'd just smeared mx-2 everywhere quite liberally & now when I tried the method in that tutorial carefully putting a thin square on the base and installing it like a label my thermals increased rather than decreased and now I'm idling at 5.3 and instead of slowly creeping up in prime95 the temps shoot up pretty fast. seems like a beep up to me.

    So I took it off again and 'lapped' it some more if that what I was doing, well I was certainly trying to, maybe I didn't give it enough wellie or elbow grease or just wasn't patient enough and now I've re-attached it on one screw up to make it even more secure but now the min temp is 4.6c rather than 0c. on the package.

    I put the thermal grease back on with a pea and an h and I didn't let it lift up while installing so I don't think there is any air trapped in there and it is on tighter than when the cpu was idling at 0c.

    Maybe the fresh stuff has to settle in. I dunno.

    Anyway in the process I found a way to get my ddr3-2400 sticks to load windows I'd been trying so many settings I hadn't tried them all yet so that could be why my CPU Is a bit warmer since I'm overclocking the memory controller by quite a wide margin.

    Prime 95 didn't pass at 4.8ghz @ddr3 2400 but I could load elite dangerous and I found that all the lag I was getting when trying to load the galaxy map just disappeared at @pc2400 speeds which is a good improvement. So what I'm going to do now obviously is try and get the cpu overclocked to where it was at 4750mhz with ddr2400 speeds and if I can get that to pass I would say it's a v.good overclock.

    & I guess I still haven't run out of things to try. If I can be bothered I could probably do a far better job on the lapping and polishing because the copper base can be unscrewed off the heatsink I just didn't want to get too radical first time around.

    Next time I might take the base off and thus being easier to handle, it will 'lap' more easily I hope.

    Turning the memory down to 1866mhz got me back to 0.0c idle just browsing and typing here so I don't think my attempt at lapping has harmed anything after all & the jump to ddr3 2400 increases my thermal load by 3-5c.
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