I like the tiny 5V fans that some people are using, but could not find one in my Canterbury Maplin.
However they did have a couple of different 40mm x 40mm fans, and I went for the (cheaper) slimline brushless one -see picture 1.
- 12V slimline brushless fan from Maplin.
- P1180726_fan-on-card_cr_en_lo.jpg (66.9 KiB) Viewed 14974 times
I have simply mounted it outside the case using super-glue (my home tool-box was over in my lab for the long-weekend), and so-far just covered the appertures each side with clear tape.
- The 12V fan mounted on the case.
- P1180733_Case_with_fan_lo.jpg (98.38 KiB) Viewed 14989 times
This is a 12V fan, and I am currently powering it from an old external USB drive supply. However it seems to run fine on 5V, almost silently, and after the weekend I will borrow a digital temperature monitor from my lab, and check the heatsink temperature running off 5V. If that is OK I will wire it into the case as per the 5V designs.
[Edited] :
Ah, of course, the FPGA has an on-chip temperature sensor. And in the Parallella example program directory there is an already compiled temperature grapher program : xtemp.
I ran this, first with 12V applied to the fan : ~59C
then with the fan stopped : the temperature rows rapidly to over 70C and was still going up rapidly,
then with 5V applied to the fan : the temperature stabilised around 69C,
and then with 12V applied again, when the temperature again dropped.
This is when basically idelling - a few windows open and xtemp running.
- Temperature graph : xtemp.
- P1180736_xtermp_en_cr_lo.jpg (71.41 KiB) Viewed 14974 times
So the question is, is about 70C OK, running from 5V ?
Or should I go back to 12V ? I might see if a bigger heatsink helps.