Heat-sink as add-on?

[Andrew2]

Amazon sells spring tempered wire.

Well, I don't want to discourage you putting as much heatsinks as possible on the board if you have fun with that.

But for everyone else who might get the impression something like that would be needed: It isn't. The components we deal here with are made for tablets (small enclosures, no airflow, never heatsinks on DRAM, PHY or PMU). There's no evidence that cooling DRAM on Allwinner boards has a positive effect (a testing methodology exists but currently not for A64 -- see here results for H3 instead). I thought while torturing Pine64 that I maybe need a heatsink on the PMU since I managed to generate power-offs from time to time... but that wasn't the culprit.

The network chip on Pine64 is used in a 'passive' mode (it's just used as PHY doing the 'physical' stuff on network layer 1 while everything else is handled inside the SoC --> no cooling needed.

The only IC that remains is the SoC and this overheats pretty fast when running heavy workloads (applies to both CPU/GPU, the video engine isn't affected since HW accelerated decoding is pretty good optimised). The good news: Unless you run benchmarks there aren't that much demanding workloads available. So better start with the Ubuntu image, install the available monitoring solution and simply watch what happens and then decide whether you need a heatsink or not.

And while it doesn't hurt to apply a heatsink (the usual cheap ones help with 10°C-15°C less when overheating occurs) in case you really plan to do number crunching on the Pine64 then you have to take care of improved heat dissipation. In general that might work using huge heatsinks like on ODROID-C2 (small board not being bent, mounting holes on the PCB and same height of DRAM and SoC -- go figure) or by simply using the very same cheap heatsinks and some controlled ventilation ('some' is really enough when you do it intelligently: one large silent fan is sufficient for 20 Pine64 -- but most of the time enclosure makers don't think about controlling the airflow and use a couple of useless and annoying small fans blowing air from here to there but not directly over the heatsink's surface)

ATTENTION: If you manage to improve heat dissipation for a reason (since you really want to run demanding workloads) you created the need to overthink powering the board: Micro USB will then be not enough but you'll have to use the Euler connector (see 2nd link in this post) since you can manage that the SoC alone will then consume more than 2A when running for example cpuburn-a53.