It appears that the CPU uses the entire bottom chassis as a heat sink, via a thick blue thermal pad stuck to the chassis.
Something similar should be possible with the NVMe. I'm still awaiting my thermal padding order, but I also ordered an NVMe heat sink which arrived today. It is basically just a thin copper plate. Installed it looks like this: https://imgur.com/gallery/koqCDJr
The heat sink kit included two thin thermal pads, which are installed between the NVMe chips and the copper plate. The plate fits almost too snugly against the magnesium chassis, so perhaps it will have good thermal conduction. I'll be testing that over the next few days. If the NVMe drive still disappears under heavy load, I'm going to try removing the copper plate and replacing it entirely with thermal pads once they arrive in the mail.
My guess is that chip->thick silicone->chassis (as is the case with the CPU) would be more efficient thermal conduction than my current setup of chip->thin silicone->copper plate->chassis since silicone would fill all gaps and thus there would be more surface area to distribute heat, even though metal<->metal thermal conduction is probably more efficient in the ideal case.
I'll report back here with my findings.
Edit: after reassembling the unit, the touchpad is a popping out a little bit because the heat sink is squeezed in there - so it's definitely too snug of a fit. It still works, but it's wonky. So I'm thinking just thermal pads will be the way to go and I'll have to do some trial and error for the right amount. It's worth noting that the keyboard and trackpad action do feel a lot less "bouncy" with the pressure of the heat sink/thermal pad inside, which is a win.
Something similar should be possible with the NVMe. I'm still awaiting my thermal padding order, but I also ordered an NVMe heat sink which arrived today. It is basically just a thin copper plate. Installed it looks like this: https://imgur.com/gallery/koqCDJr
The heat sink kit included two thin thermal pads, which are installed between the NVMe chips and the copper plate. The plate fits almost too snugly against the magnesium chassis, so perhaps it will have good thermal conduction. I'll be testing that over the next few days. If the NVMe drive still disappears under heavy load, I'm going to try removing the copper plate and replacing it entirely with thermal pads once they arrive in the mail.
My guess is that chip->thick silicone->chassis (as is the case with the CPU) would be more efficient thermal conduction than my current setup of chip->thin silicone->copper plate->chassis since silicone would fill all gaps and thus there would be more surface area to distribute heat, even though metal<->metal thermal conduction is probably more efficient in the ideal case.
I'll report back here with my findings.
Edit: after reassembling the unit, the touchpad is a popping out a little bit because the heat sink is squeezed in there - so it's definitely too snug of a fit. It still works, but it's wonky. So I'm thinking just thermal pads will be the way to go and I'll have to do some trial and error for the right amount. It's worth noting that the keyboard and trackpad action do feel a lot less "bouncy" with the pressure of the heat sink/thermal pad inside, which is a win.