From this link below:
You can see that the PCI is Revision 2.3
From the link below:
Revision 2.3 is an evolutionary change to the PCI Local Bus Specification. Revision 2.3 makes a significant step in migrating the PCI bus from the original 5.0 volt signaling to a 3.3 volt signaling bus. Revision 2.3 supports the 5V and 3.3V keyed system board connectors (as did revision 2.2) but revision 2.3 supports only the 3.3V and Universal keyed add-in cards. The 5V keyed add-in card is not supported in revision 2.3. PCI 66, PCI-X, Mini PCI, and Low Profile PCI support only 3.3 volt signaling on 3.3V keyed system board connectors and 3.3V and Universal keyed add-in cards.
I hope that this will help you.
All the best,