Lapped bareback?

[piratemonkey]

Presuming that there is a near perfect lapping job done on a CPU and cooler, could I run it 'bareback' (without thermal paste)?

My current understanding leads me to think that there would be no reason to have thermal paste, and may even affect it negatively due to there being an unnecessary layer for heat to go through.

Would there be better thermal transfer, leading to better thermals due to there not being that extra layer?

Is it right thinking that the thermal conductivity would be that of copper (due to that being the metal exposed on the CPU and cooler)?

[BobVonBob]

Assuming almost absolute perfect flatness, yes. We're talking optical flat levels of flat. Even then, heat expansion would probably cause enough movement to create poor contact. In the real world use thermal paste, heat transfer between two non-conforming objects was never meant to be.

 

Assuming it did work, which is a very bold assumption, thermal transfer is a maybe because nobody has studied this before as far as I can tell, but I'd suspect yes it would be better given the IHS and cooler would nearly be a single piece at the levels of flatness required. And yes, the thermal conductivity would be that of copper.

[TheBean]

who knows... if you make it 100% flat (impossble in reality) you reduce the surface area of the cpu. that means less area for the heat to transfer from.

[HM-2]

2 hours ago, Saksham said:

if you make it 100% flat (impossble in reality) you reduce the surface area of the cpu. that means less area for the heat to transfer from.

This, whilst technically correct, rather misses the point; the surface area for heat transfer is only relevant if there's something for it to transfer to.

The infinitesimally small decrease in surface area you may get from lapping a CPU will be massively outweighed by the potential for better contact.

[piratemonkey]

11 minutes ago, HM-2 said:

The infinitesimally small decrease in surface area you may get from lapping a CPU will be massively outweighed by the potential for better contact.

I would think that if the IHS has less material (especially with it being only copper when lapped) then it would be better. Theoretically of course

[HM-2]

1 minute ago, piratemonkey said:

I would think that if the IHS has less material (especially with it being only copper when lapped) then it would be better. Theoretically of course

Agreed- the less material between the object actually producing heat and whatever is being used to dissipate it the better.