There is one simple rule to be applied when assigning the SID and SVID for PCI devices integrated on a motherboard. It is required that all new motherboard designs have a new, unique SID assigned by the manufacturer. The operating system relies on being able to uniquely identify a device and each implementation of that device. They ship 700,000 systems before the problem is discovered. In order to apply a fix for the Windows operating system that does not adversely affect every component using the south bridge, the device and implementation must be able to be uniquely identified.
Some events require the SID of a motherboard to be updated.
However, an installation of an updated chip that has followed the ID rules for devices can cause a change of the driver for that chip due to a new Plug and Play ID being read, for example, if the REV value changed from 1 to 2. Any component value changes on the motherboard, including resistors and capacitors. Any SKU change, for example, a motherboard SKU that removes an integrated modem that was on the board when the SIDs were originally assigned. The DID is a value assigned by the device manufacturer that, in conjunction with the VID and REV values, uniquely identifies the PCI device. If an existing device is integrated into a new multifunction package, the DID for that device must change.