Ever since the bios update to the new platform with version .099 it is no longer possible to program against the Recording Led (or Programmable LED) of the htpc header.
The LED used to be controlled by the WMI class WMIAcpiPlatform. Unfortunately, this class is no longer being made available to Windows (7 & 8, x64) by the Bios it seems.
Please fix this or provide an manual downgrade path to an older gen bios version.
Thanks, but please note that I'm actually referring to a completely different problem related to the new bios platform and the htpc header (and not detection of a pci-e device like in the thread you've linked to above).
Unfortunately, once you installed BIOS 0099, due to the structural changes in this BIOS version, it will no longer be possible to downgrade the BIOS to any earlier versions.
Please check the private message I sent you.