I've removed that heatsink, just realizing that I should have paid attention to the thermal image from the Kickstarter page:
https://www.kickstarter.com/projects/ad ... sts/703717You can see that there are two small chips north and south of the Epiphany that get quite hot, and one of them was under the heatsink without touching it. I have the fan blowing from that side so some air was getting there, but I suspect that it was worse than having the whole area open with the air flowing freely over it.
The image I had in mind was this other one, but it's for the Gen0 board, not the Gen1:
http://s.radar.oreilly.com/wp-files/8/2 ... 00x232.jpgI might have been transferring heat from the ZINQ to the Epiphany, which is probably as bad an idea as it sounds.
There is another problem:
the ZINQ chip is slightly taller than the Epiphany. I had adjusted it with a piece of aluminium foil slightly thicker than the kind used for packaging food, plus a thin layer of Arctic MX-2 thermal grease, but then the HDMI chip is again a little bit taller than the ZINQ, so there is no way to have it completely level unless you start piling risers or thermal pads.
(Edit: ZYNQ and Epiphany are level as far as I can see. The one tilting the old heatsink was the HDMI chip)I've put now a different heatsink similar to the original but 20x30x30mm big that rests only on the ZINQ and touches the back of the Ethernet plug. The temperature with the same fan on, but without the top side because it won't fit, is a couple of degrees lower: 45C to 43C. I don't know the ambient temperature but it's a warm day.
With the fan blowing I can touch the Epiphany without issue, it feels hot but it's no problem keeping the fingertip on it even after it has been computing things for a while.
So again, if you are thinking about doing this, don't.