If it not effecting the PC adversely then it is just a message on the post BIOS screen, you can remove post messages in BIOS as long with the F2 and F12 post messages, so be careful to just turn off the right message.
The "PCI Express Advanced Error Reporting" feature can be set to "Enabled" or "Disabled". If it is set to "Enabled", the operating system will check the PCI device drivers. The messages that are returned as responses still cannot be cleanly processed by all operating systems. Our Quality Assurance department sets the feature to "Disabled" to avoid problems during operating system installation.
When you reformatted and re-installed you turn this feature "On" by default, The Quality Assurance department wasn't there to set it.LOL.