I tried removing the case and flipping the fan direction and noticed a reduction in temperature (from 40 down to below 30 °C), however I did not notice an improvement in hashrate (it remained between 7.0 and 7.2GH/s)
What did seem to have an influence though was the temperature of the chips when it is powered up.
For example, when it was hashing at 7.15, at 40°C, I powered it off, waited a few seconds, then powered it back up and noticed the hashrate was lower 6.9 GH/s
Someone mentioned that the Jalapenos performs some sort of capability sweep at power up, so I was wondering if starting them from colder may have a positive effect.
So I chilled the Jalapeno in the freezer for about 20 minutes (unpowered), took it out and then powered it up as usual - this time it was hashing 7.6 GH/s - and has continued to do average this for the last 36 hours. I am now to afraid to try the process again in case it was a one-off fluke power up state of the chips that I may never see again
so in summary for me (recent 7GH model)
1. the fan trick did not provide any noticeable hashrate increase, but brought the operating temperature down lower.
2. There is a slight possibility that powering up the Jalapeno from a lower temperature may provide a higher chip operating setting. YMMV
