If you have an HP Microserver N40L or N54L, and want to upgrade to Windows 8.1 or Windows Server 2012+, please ensure you’re first running at least the bios released in October 2013, otherwise you WILL have issues with the onboard NIC. The latest bios solves the problem.
Problems you may encounter otherwise: Windows installer will sit forever at “Getting devices ready”.
If you disable the onboard NIC, install Windows and re-enable the onboard NIC, the NIC will just say ‘Cable unplugged’.
An entitlement is required to download newer bios updates (Gee, thanks HP), but if you do a bit of basic googling, you should be able to find links to download the bios. Very easy to find in the case of the N40L - and it’s an HP download link that bypasses the entitlement requirement, so nothing dodgy about the file.
