I would be really interested to see if there are any temp differences between a 220 grit lap and a 3000 grit lap. Has anyone done a comparison to see if lapping to a shinny finish is better?
I'm thinking the flatness of the surfaces may account for all the thermal transfer improvements and the polished surface does nothing but look nice. I would love to see some data on that though.
Excellent thread as always IDC!
Years ago, back in 2007, I purchased five Q6600 CPUs and built five identical quad-core rigs. I lapped all of them, and the Tuniq120 towers I bought to go with them, and comfortably OC'ed all of them to 3.3GHz.
In the process of lapping those chips (I was interested in the statistics of OC'ing at the time) I systematically checked the temperature reduction gained after every grit and found the bulk of the benefit came from the grits up to 800, but nothing was really gained after that.
I wasn't into documenting or publishing my results at the time so there are no threads or links for me to point you to, and I doubt I even kept any of my notes from so long ago.
You could call it quits after just 220 grit and still have around 80% of the benefits. It really is just a matter of getting two warped/uneven surfaces to be flat, the surface roughness itself (the scratches) is not as big of a deal as you might otherwise think.
Another excellent article IDC! This really should be on the AT frontpage IMO.
So the lilac rows are where you've basically used your lower temps after lapping to hit a better vcc while remaining stable? Or least that's what I read. Pity it's just yourself doing this because I could think of a few more tests you could have run :biggrin:
For one thing I'd love to see would be how this affects underclocking: would your non-lapped vs lapped be able to run stable at say 2.0GHz with a lower voltage, and how much?
The second thing is which I'm sure you're going to get around too: overclocking past 4.4GHz. And unfortunately (unless you ran some figures and left them out) now that you've lapped it I can't see how you can get the figures for - say - 4.8GHz, 5.0GHz etc. before lapping. In other words now that the original is lapped I assume we will only be able to guess the results of 5.0GHz pre-lapped vs lapped. I guess it will may (should) be more than 10°C.
Thanks for the kind words :$
It is true, I did not collect >4.3GHz data for the CPU prior to lapping...but the reason I didn't is because my NH-D14 and H100 are already lapped. It makes little sense to lap just one surface versus lapping both. That is why I lapped both the IHS and the stock HSF before testing to compare to the non-lapped stock case.
Everything I own that could get the 8350 to 5GHz was already lapped, the only thing that wasn't lapped was the CPU itself and the stock HSF. Now that everything is apples-to-apples it is time to get that chip to 5GHz. (but I'm intentionally waiting until tomorrow before I remove the stock HSF because I need to get some sound measurements with the stock HSF per sandorski's request)