DO NOT MAKE THIS MODIFICATION! It may burn out your fan or worse, brick your pod!

Keeping the fan running at a lower speed cools and keeps the GS5 at room temperature while overclocked/over-volted for increased hashing performance. I have 6 of them running this way off of 5V USB power and they are just fine! And ELECTRICALLY SOUND and CORRECTLY powered!

IF you absolutely must run your fan at a reduced speed/rate/cfm, use a Voltage Regulator Made To Do The Job between 12V and your fan.
There are plenty of them available on the net. An LM7806 6V regulator, with a 100nf cap connected between input and ground and output and ground, soldered together and wired according to its PDF datasheet.
Insulate as needed.

The regulator will not get hot, not hardly even warm except for the power it dissipates from dropping 12V, actually 13.8V to 14.2V DC to 6V DC.

There are also mini DC voltage regulators sold on eBay that wire in between the 12V +/- rail and the fan so you can manually adjust it's speed or automate it via temperature sensing.
You can search for it on eBay using '12v dc fan speed regulator'
They cost a few bucks.
Anyway, DO NOT make the suggested modification per this diagram in the picture!
It could ruin your fan, cause erratic operation, voltage fluctuations or worse, brick your pod!

Making any modification to your pod is strictly at your own risk and responsibility.

If you want a qualified technician to make your modifications for you, PM me and I will be happy to assist you in doing so!