I started my other com, where I too use realtek hd audio.
I had a long hard look. I took out the speaker-jack, and program told me it was out.
Can I be sure of, you got the right jack, in the right place?
Of course you did that!
Re: The problem is that all my jacks in the manager are greyed out
I googled those words and found (your post) and:
I have no fix for this, the only thing that has worked for me is to restart,
go into the BIOS, disable the onboard audio, boot up, restart,
and go into BIOS again and re-enable it.
i tried all the different drivers i could get my hands on from asus and realtek, but none worked.
You could try this, otherwise, goggle:jacks in the Realtek High Def are greyed out
or the like
You are not alone with this problem
Personally, if it was my problem I would get a soundcard.
This will too free some resources on the system