I replaced the stock fan (noisy!) with a 2"x2"x1.5" heatsink, attaching it to the die with some phase-change thermal interface material and squares of thermal gap pad on the RAM chips so that everything sits level. Temperatures seem high but acceptable - around 45-50c at idle, ~78c with either the GPU or CPU loaded, ~82c with both loaded (smoke sprite demo + ‘stress -c 4’). Still higher than I’d expect for a mobile part (how do they plan to dissipate that in a phone form factor?) but everything seems perfectly stable.
I installed the SLF-40 and the mounting holes and pushpins fit perfectly. The fan is a bit quieter than the stock fan but still not that great. However, I installed a fan speed control that I had and set the fan speed to minimum and it is almost silent, very very quiet. The temperatures generally stay pretty cool, snapshot below taken while mostly idle doing this post.
ubuntu@tegra-ubuntu:~$ sensors
CPU-therm-virtual-0
Adapter: Virtual device
temp1: +36.5°C (crit = +101.0°C)
