Critical heating issue

[aolofsson]

Hi,

This post will address potential overheating issues that you might encounter with your Parallella board and how to overcome them.

First if all, some power measurement data points, all measured at the 5V input to the board:
-Power with Epiphany clock gating turned in 0.92. This is currently not enabled on the SDK but an example can be found on the epiphany-examples directory.
-Power without aggressive epiphany clock gating is 0.97.
-Power with USB devices plugged in..depends in what you have plugged in, could easily be 1.3 A.
-Employ some other cooling technique, like mounting the board to a metal plate.

Best practices for ensuring stable operations and a long operating life:
-Use any type of fan, a gentle breeze should do.
-Install the heatsink on the zynq
-Install a second heatsink on epiphany
-Put the board on its side to improve natural convection.
-Use a powered USB hub (in a safe way)

Some of these power issues are due to the early version of the zynq being used. Going forward, the new production version of the zynq will have less standby power and the situation will be better yet for the zynq 7010.

We will also keep working on tuning the FPGA load and the rest of the firmware to further reduce the default power.

Andreas

[tnt]

wrt to USB: Whatever you plug on USB should change the temperature that much. Even assuming a rather large 0.1v drop from input to device, that would still be only 50mW...

For the rest, this seems within spec to me. Of course heatsinks or fan might be a good idea, there is no changing the laws of physics and dissipating 5w from a credit sized board isn't going to be magical. However I would not pre-attach the heatsink. It's easy enough for the customer/backer to attach himself and if you want to use your own heatsink, it's not necesserely easy to remove depending on the glue (and could even put undue stress on the BGA).

[magorian]

Thanks for the power info and tips. Is there anything that reports cpu or system temps on the board? Sensors-detect of the lm-sensors package bombs out looking for /sys/bus/pci/devices so obviously that's x86 dependent. Definitely crashes less and doesn't get boiling hot with a fan on it. Dan

[tnt]

[magorian]

> The zynq has a built in temp sensor that can be accessed from linux if the device tree if properly setup.

Any tips on making that work with lm-sensors for those of us not Zinq-savvy would be appreciated, given the extreme heat even if it is within spec, for people not planning on using fan cooling who want to keep an eye on it.

I think I will need to supply 80 mms with the clusters to the users: one keeps repeatedly crashing without, and tipping it on its side with the bottom lifted for better convection doesn't really help much, as well as looking funky. Probably ought to supply heat sinks for the epiphanys too, tho that also may not be enough.

Dan

[Transcendental]

During the Kickstarter campaign I ordered cases for my Parallella boards. How (extra-) problematic is the Parallella's heat dissipation when encased?

[hewsmike]

Looking at the it would seem the ( very nice ) logo is the ideal spot to plonk a fan? But the top and bottom panels do appear to be interchangeable. If you carefully drill-out/fashion a circular opening of suitable diameter, plus small holes for mounting screws, a stock sized fan of your choice could be placed on the plain panel. And you keep the logo! Run it on it's side as suggested, and if it tends to flip with the fan pushing laterally then mount the whole upon another piece of wider acrylic as a base.

As I've yet to see/feel a board, could any that have kindly comment ?

Cheers, Mike.

( edit ) For that matter, do the heat sinks suit the case well ?

[magorian]

Guys, judging from how extremely hot mine get in the open on standoffs, until something changes I can't even imagine it in a case w/o fan cooling. Dan

[Transcendental]

Thanks for the input, Mike and Dan. It'd be good to get Adapteva's take on this as well.

[greytery]

Confused by Andreas' note:

1. Do the words "-Install the heatsink on the zynq" mean that a heatsink is supplied?
2. "-Install a second heatsink on epiphany ..." - what heatsink specs/dimenions are recommended?
3. Would any of the other chips benefit from sinks?

Was expecting heat some issues anyway, because Pi has some - or at least there's a ready market in heatsinks for those who want to pimp up their Pi or even O/C it.

Maybe I should have gone for the free t-shirt instead of the free case It may get a bit warm in here.

greytery