Quoted from: https://www.anandtech.com/show/556/8

PCI IRQ Sharing and Frequency settings

The AX6BC Pro features 5 PCI slots, all of which are bus master PCI slots.  Four of the five slots are capable of accepting full length cards while the fifth slot is blocked by a 3-pin fan connector. 

The board shares IRQs just like every other board, the first and second PCI slots are shared with the AGP slot.  The fourth and fifth PCI slots share an IRQ with the on-board USB controller, and finally, the third PCI slot is the ideal one to install your PCI peripherals in since it does not share an IRQ with any other slots. 

The AX6BC Pro Gold features a fully jumperless CPU configuration utility present in the BIOS.  While it is definitely not as flexible as the ABIT boards in terms of the number of options present in the BIOS setup, it is decent in that it provides you with all of the options you need to get up and running, including FSB and core voltage tweaking.