What is the A side, B side configuration of PCI cards and what VIO version should one order?
The Component side of the PCI card is the B side, and the solder side of the card is the A side. If looking from the back of the system chassis, the B side is on the right and the A side is on the left. The PCI bus has 5V, 3.3V, 12V, -12V and VIO on the bus. The VIO is intended as the power to the PCI bus interface controller ICs. The VIO could be either 5V or 3.3V, depending on the motherboard PCI expansion slot design. The PCI expansion slot connector is divided into two sections by a plastic divider called the “key”. If the key of the PCI expansion slot connector is located near the back of the chassis then the VIO for that slot is 3.3V. If the key is located closer to the center of the motherboard, then the VIO for that slot is 5V. Most of the 32 bit PCI slots are designed to be VIO=5V. For the 64 bit PCI slot, an additional key is placed between the 32 bit section and the 64 bit extension, dividing the connector into 3 sections. However, the identification of the VIO for the 64 bi
