Thermal pastes to heat pipes?

[GL9106]

Is apply thermal pastes to the heat pipes better than on the CPU because you can guarantee that the thermal paste will make contact?

 

[dudio]

I've always applied it to the CPU, but believe applying to the heatsink makes more sense.

 

[Eximo]

Many factors in the interface.

Typical rule of thumbs:

Plated/Polished base, small amount of a more liquid thermal compound to the CPU.
Machined surface, small amount of a moderate thermal compound to the CPU.
Direct contact heatpipes(Machined flat) , small amount of a moderate thermal compound to the CPU.
Direct contact heatpies(gaps, or aluminum base between pipes) generous amount of thick compound applied to the CPU and the filling gaps in the heat pipes.

For Intel the application of the thermal compound is more important in the vertical, (parallel to the I/O on the 'back' of the motherboard) So a common tactic is a thin bead applied in a vertical line.

Ryzen has two dies, so applying compound over the entire heatspreader isn't the worst idea.

On rougher surfaces I like to apply thermal compound with one of the above methods, tighten the cooler down, then remove it to check spread. Then wipe it gently, leaving compound in the gaps. I've found that second applications do much better then first. So when best cooling is desired it is worth the waste.

And it is best to read the instructions included with each compound. Used an applier/spreader nozzle on my last installation.