Your chipset drivers are here:
Driver

I'd also try this beta 177.92, It has lots of improvements, some of which can be read about on the download page:
GeForce Release 177


As for the bios:
Instructions on how to flash yours is here:
http://support.asus.com/technicaldoc...Language=en-us
(second one down)
On this page is links for all bios updates plus more information (down the left hand side)
http://support.asus.com/download/dow...us&model=P5N-D

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