Only the 3B+ SoC has it enabled by default. The newer 3B boards that have the 3B+ SoC also probably have it enabled by default but I've not checked.
The 4 needs a bootloader firmware update which isn't ready yet.
Older Pi boards like the Zero don't support USB booting directly as the internal boot ROM doesn't have any support for it. You can partially work around it by putting bootcode.bin on a SD card. The rest of your install is on the USB drive.
It is the same mechanism. The problem is that some drives work slightly different or need a longer initialisation time.
The mineral oil will get everywhere and start wicking up cables. You need to take special precautions when using oil immersion cooling because of this. I expect it to be a leaky disaster with a FDM 3D printed case. Oil immersion cooling isn't practical unless your situation absolutely needs it e.g. high voltages. Any PC builds using it are doing it for show purposes.genodesiful wrote: ↑Sun Sep 29, 2019 2:52 pmI'm going to try This could have excellent applications for SBCs, since they have no mechanical parts... Maybe that's another case I'll considering making, also with all the connections (SD reader, USB, GPIO etc) extended and incorporated into the case chassis walls, so you never have to deal with touching the oil...
The oil is just to transfer heat from the device BTW. You still need to cool the oil itself if your device generates enough heat to raise the temperature of the oil significantly. You'll eventually get a fish tank full of hot oil and very poor cooling for the device inside.