wrote:

MY GA-MA785GPM-US2H motherboard has a connection called a
North Bridge Fan Header'. What, pray tell, connects to there?

http://en.wikipedia.org/wiki/Northbridge_(computing)

It's for a fan on the northbridge chip. Not all mobos use a fan.
Depends on how much heat can be dissipated and if quickly enough using
just a good heatsink, or by using vapor tubes to combine the cooling
between CPU and chipset.

http://www.geek.com/wp-content/uploa...5gt_ud3h_1.jpg
http://www.gigabyte.us/products/prod...px?pid=3150#ov
(didn't find a -UD2H model)

Seems Gigabyte believes the stock heatsinks on the chipset without fan
is sufficient for cooling or may rely on the CPU's HSF to provide some
additional airflow. They may not have planned for overclocking.
There's a good chance that a fan won't fit atop the NB chip because the
CPU's heatsink would be in the way. Fans might be used on the SB chip,
especially if the mobo has onboard video.