• Effectively, a PCI parity error occurs if a PCI transaction suffers corruption.

  • Parity data is generated on all PCI transactions.

  • From the PCI bus specification: "Parity generation is not optional; it must be done by all PCI-compliant devices."

  • Parity checking during data reads is also mandatory on all devices except those which will never be included in add-in cards (i.e. motherboard or chipset-integrated devices), and "temporary data" devices (e.g. graphics adaptors).

  • Many BIOSes do not enable PCI parity error checking (EDAC does).

  • Unreported PCI parity errors are very bad news for devices like PCI hard disk controllers.

  • You may well have experienced PCI parity errors in the past (it's just that your computer didn't tell you about it!).