I've had a Windows 7 machine A7n8x motherboard with Realtek HD Audio working with no issues at all for a while with the little option available to disable front panel detection.
I think there was a Windows Update driver
change that updated my realtek drivers
and now that option has disappeared... and my front panel behaved differently.
I had to work around what used to be possible to configure from the Realtek HD Audio manager by going into my bios (as mentioned earlier in the forum) to enable AC97 audio... This seems to allow the front panel detection to remain on at all times, and I've also selected 'Device Advanced Settings' in RHDAM to 'Separate all input jacks' and 'Make front and rear output devices playback two different audio streams simultaneously'.
The previous poster reported that if he pushed in the headphone jack into the front panel it seemed to detect, so he wondered if it were a hardware problem... I think this is a red herring, as I experienced the same behaviour and briefly thought the same, but the connection would be extremely flakey and the slightest touch would send the computer into a detect/not detect loop, but like I say, I knew that my front panel was working fine before this phantom driver update, and implementing the above I could get the headphones working fine also, so it can't be a bad connection?
My only problem now is that it doesn't autodetect that I've plugged headphones in, and switch to the headphones as a default device, I have to manually open the RHDAM and set the default to my headphones (front panel), or surround sound (back panel) before being able to work. Not the end of the world, but am irritated that a driver update has essentially made me take a step backwards.
I could try to uninstall and install the older driver, but have spent too long on this now, I rarely use headphones (when I manage to wake before our toddler!), so will live with the workaround.