I finally did it ...... lapping (56K may struggle)

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Yep, I finally grew the balls to lap both my Zalman 9700NT and my Q6600!!!!

Supplies:

Wet & Dry sandpaper
600 grit - 1 sheet
800 grit - 1 sheet
1200 grit - 1 sheet
1500 grit - 1 sheet
2000 grit - 1 sheet

Piece of 6mm glass (300mm x 200mm)

Masking tape

I taped the paper to the glass to prevent any movement and made a "backstop" (two nails hammered into my workbench) to stop the glass moving.

Here is the 9700NT stock base, all very nice and shiney but is it flat??
.

dscf0453rel8.jpg


dscf0454rgn0.jpg

I started off with some 600grit wet and dry paper, the method I started using was 5 passes then rotate the base 90°, 5 passes, rotate 90°, five passes etc until all four axis have had the same amount of passes.

NOTE: I used this method throughout the lapping, from here on in I'll no longer refer to the 90° rotation just the number of passes, please be aware that the rotation takes place everytime the number of passes in each direction has been completed. A "pass" for this operation is moving from one end of the sheet to the other in a single motion/direction and does not include a return pass, in the interest of technique I went in one direction only. The weight of the heatsink is sufficient downward pressure so there is no need to "lean on it" in an attempt to speed up the process, slow and steady is required.

So after 5 passes we see some results in the pic below. The cooler base is noticably concave with the corners being the high points, not really conducive to a good mating surface is it? the potential for air to be trapped in here is huge.

dscf0457ruq9.jpg

Given the amount of concavity I decided to increase the number of passes to 10 in an attempt at being finished sometime this week. Honestly, impatience is your worst enemy while doing this and even though I was fully aware of what is required I found myself becoming impatient. After 10 more passes we end up with the pic below, gonna be a long day.

dscf0458rem3.jpg

10 more passes and we see the pic below, it was after this I stopped taking pics and continued until the chrome circle was the size of a fingernail using all grits until I was satisfied the base was "flat". To test for flatness a razor blade held on edge across the surface then held up to the light will display any irregularity, well good enough for the naked eye anyway.

dscf0463rfw8.jpg
 
Next was the knee trembler, not for the faint hearted assuredly, lapping the Q6600.

I started off doing this with a 1500grit to get an idea of the surface profile, the result was interesting to say the least. The IHS was convex with a definite "mound" corresponding to the chip underneath, there was then a concave "valley" before the edge of the IHS which appeared to be roughly the same height as the "mound". Not a good surface profile at all.

I was getting impatient (again) to see what the resulting operating temperatures were going to be so photography went out the window at this stage, suffice it to say I followed the above procedure until I had achieved my desired result. (to be honest I was crapping myself I'd bugger up the chip and was quite happy when this was completed)

Having satisfied myself no more could be gained by continued sanding I cleaned up the surfaces using isopropyl alcohol and cotton buds. It is imperative to do this thoroughly washing the surface in multiple directions to remove all the sanding dust. Once I was satisfied with the cleanliness I applied some MX-2 and reassembled.

What was the point I hear you all say, I was after lower operating temperature and higher overclocking headroom as a result. I now have my cpu @ 3.0GHz at 32°C idle and 49°C under full load. See below.

tempidle30ghzlf6.jpg


load30ghzafterlap2rpf7.jpg

I'll get some pics of the finished surfaces (both cpu and cooler) when I pull them apart next time. (going to lap a Zalman CNPS 8700LED shortly for comparison to the 9700NT)

Also more overclocking to come, my biggest enemy here (using air cooling) is the Australian summer temps, we're regularly over 30°C at present and it's only spring so I'm restricted to late night/early morning ocing. I've also ordered some new ram as I believe the ram is a weak point in this build, no because of quality but capacity, I'm replacing my Kingston HyperX PC2-6400 (KHX6400D2LLK2/2G) with some Kingston HyperX PC2-9600 (KHX9600D2K2/2G) which should arrive later this week so I'm hoping for an improvement with that. (at $A275 incl shipping it better bloody improve)

That's how I spent my saturday

:D
 
The RAM will help tremendously. What is lapping? Are you trying to improve the cooling properties of the heatsink? Oh, lol nevermind. I found the answers in the second post. Try to squeeze more out of the Q6600 if you can and post the results.
 
Nice, I may want to do this on my 5000+ how much did all tat sand cost

The RAM will help tremendously. What is lapping? Are you trying to improve the cooling properties of the heatsink?

lapping is when you sand the CPU and HS down to a mirror finish to make it have better heat conduct
 
The RAM will help tremendously. What is lapping? Are you trying to improve the cooling properties of the heatsink? Oh, lol nevermind. I found the answers in the second post. Try to squeeze more out of the Q6600 if you can and post the results.
I have been up to 3.6GHz though not completely Orthos Stable, one core kept crashing, I'm hoping to get 3.8GHz or (dare I dream) 4GHz

Nice, I may want to do this on my 5000+ how much did all tat sand cost



lapping is when you sand the CPU and HS down to a mirror finish to make it have better heat conduct
Sandpaper was $A6.00 lol, also mirror finish is nice but the real goal is flatness

Wow, I can't believe he did it to the CPU heatspreader too!!!!
That's where I needed to grow the balls, I was "aprehensive" about it to say the least

What was the temps before?
I gained ~6-7°C idle and ~7-8°C load, it depends on the time of day but those differences are probably average (I didn't make a note of the time of day that I took the before readings)
 
Still, that's pretty impressive. Especially coming from the exact same heatsink/fan. Most people get that kind of gain from buying a new cooler all together :p.
 
Given the degree of unevenness between the two surfaces prior to this I'm actually surprised the temps were as good as they were.
 
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