I’m running 4.4.52; I can hold my thumb on the CPU for around 5 seconds, then it heats up too much (due to my thumb is working like insulation).
I have no fancy heatsink (and I refuse to use those double-sided tape that work as heat insulation – if you want to put on a heatsink, please use real heatsink compound – yes, the expensive stuff – and apply only a 1/25mm thick layer on the surface of the chip).
My ubuntu has been running for several days; I’ve been watching star-trek from a harddisk attached to the EspressoBIN via netatalk over the network and it has not been unstable so far.
As for serial console, I bought two boards; the cable that came with the first board is working alright, but the second cable is junk.
If possible, try measuring the resistance in the cable (it should be way too high). I recommend cables from Kenable; I now have two of those and there are no issues with those.
As for Armbian, I’m still waiting for my cheap China.micro-SD-cards – yeah, I know, but I’m not going to write to those very often, so I think they’ll be likely to last at least a week each. 😉
(I’ve attempted to Franken-install Armbian via the network, but it got a bit too messy, so I better wait for those cards).
Oh, btw: If you’re not using a 3.5 inch SATA drive, you can use a 5.9V/3A switchmode PSU.
I’ve had some problems with one PSU. Switchmode seem to be a little unstable; old heavy PSUs are doing a little better (so far).