Created on: April 23, 2013
Last updated: August 25, 2015
You may find that the performance of certain PCIe cards (most commonly eSATA cards) will benefit from modifying the bandwidth of the PCIe slot that holds the card. For the 2008 Mac Pro and earlier, you can use Apple's built-in Expansion Slot Utility to customize your PCIe port configuration. Please see the link below for more background on this process.
http://support.apple.com/kb/HT2838
