No sound through HDMI but no option to choose it as default

Well I have a problem with my HDMI Sound output, I had Vista and it was fine to use just plugged it in chose HDMI and the sound was fine, I then upgraded to 7 and now the option doesn't even come up for me to choose it, I thought I would point this out since other people have the option but it's greyed out, does anybody have a solution for this at all? thanks guys.

Did you install the Windows 7 drivers for your video card? I have an ATI HD4850 installed right now (had an NVIDIA GTS450) and when the Video card drivers were installed it also installed the sound drivers for HDMI.

How will I be able to check if they updated during the upgrade?
I went into device manager and selected update driver for both options but they said they were up to date

You didn't list many System Specs but in most cases going to the Video vendors downloads and installing the latest download is the best way. Windows doesn't always find the latest or best drivers. Acer doesn't always have the latest either (I have an Acer Aspire 7720).

One thing I overlooked, in the Sound Playback panel, RIGHT click in a blank space then check both options for disabled and disconnected devices and then see if the HDMI sound is displayed.

Hey sorry I took so long to reply, i've not had chance to fully fill out the system specs and I did do as you said they were both enabled, but I have found the solution for this for anybody that has this problem of no sound through their HDMI cable you need to go the intel website and find in the downloads page an automatic scanner which scans the drivers and checks if they're up to date update your drivers and in one of them is a HDMI sound driver, after they are installed your laptop restarts and when it starts up sound is going through the tv

Audio Driver Update worked for me (Here is how)

Hello

I had intermittent detection of the HDMI in "Control Panel/Sound", and eventually no detection (the following solution may also work for those who were never able to obtain a signal at all). For me updating the audio driver fixed the problem. You can update the audio and video drivers by following the steps below (found these steps at Microsoft website). My computer is only 6 months old, but still needed the drivers updated. No special system setting are required as written in previous posts, if the driver is the problem. I was also extremely frustrated with the ongoing problem and hope the driver updates work for you. Good luck!

1. Open Device Manager by clicking the Start button
   
   , clicking Control Panel, clicking System and Maintenance, and then clicking Device Manager.*
   
   If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
2. In Device Manager, locate the device you want to update, and then double-click the device name.
3. Click sound video and gaming controller
4. Open each audio controller in sound video and gaming (one at a time) and update by Clicking the Driver tab, and then click Update Driver and follow the instructions.