lapping help (see pic)

So this is how my i7-920 looks after 600 grit. All the aluminium has gone but the thing is you can see that there is like a lip at the side where its deeper and the sandpaper hasnt really reached it yet. Should this be left there or should I keep sanding until the entire thing is flat including the edges?

Are you lapping on the "wood" table ?

Boulard83 said:

Are you lapping on the "wood" table ?

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Yea, never lap on a wood table. The best material to use is plate glass because it is perfictly flat and smooth

noooo im lapping on a glass sheet, i just took it off for the photo.

so what about the sides? are they ok like that or i need to keep going until the sides are flat too?

When you place a razor blade across it, does it confirm that the edges are in fact raised, in other words concave?

It could be that the original shape was convex and now you've acheived flatness without taking too much metal off the edges.

My AMD chip did the opposite, with the middle being the last thing to show copper.

The finer grits aren't going to take that much depth off the chip anymore than it already is. The idea once you get to copper is to smooth it out, not get deeper and deeper. The pressure at which you lap at comes into play here.

Porvalsh said:

When you place a razor blade across it, does it confirm that the edges are in fact raised, in other words concave?

Click to expand...

no the sides are lower than the middle, so convex.......so should i keep going until its totally flat including the sides?

also are you rotating the cpu 90 degrees after each 20-30 strokes

Jolly-Swagman said:

also are you rotating the cpu 90 degrees after each 20-30 strokes

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yus

If these edge are lower, Your fine !

It can be your lapping that is wrong, Maybe when you go from UP to DOWN you accidently scratche the edge ? this cause these edge that are lower.

I have never lapped an i7 chip but I'd keep going. My last lap job was the opposite of yours, with the sides being the high points. With the AMD chips though, you just go until there is no Nickel showing anymore, just pure copper.



I've never lapped an i7 though.

BTW. If you want to, you can always stop and install the CPU back into your system. If you don't see any results from lapping then you can continue trying to flatten it a bit more. If the razor blade doesn't show light expect for right at th edge of the chip, then you're probably ok. Just so its not showing light in the middle of the chip.

EDIT: After reading some other threads and forums about lapping the i7 it seems like some people go overboard, lap too far, and end up with poor results. It seems like for the i7 there is minimal gain from lapping, which means that the chip generally comes very flat from Intel.

In my own lapping experience, I have gotten only 2-4C. In some of the threads I've read, lapping the CPU too far has even contributed to higher temps than stock. With that being said, perhaps you would want to avoid going too far and simply polish up that finish a bit.