This is driving me nuts. I've put a few man hours into trying to figure this out.

I have:
Uninstalled drivers
Reinstalled drivers
Installed XP, Vista, 7 drivers at different points
Run into every single jack on the back of the sound card
Used different cables
And probably more shit that I can't think of

This goddamn sound card worked in XP without a hitch but when I upgraded to Win7 (fresh install) I can't get it to work.

It's a Realtek High Definition audio onboard card that came with my Gigabyte M61P-S3. I've run the drivers from the disk, from the website, and from a myriad of other places. Nothing works.

Device manager shows no problems with Realtek High Definition Audio but DOES show a question mark under "Multimedia Audio Controller."

This is driving me up a wall. Any ideas?

The only thing I can think of to try now (which I will do if no one else on the internet has any better ideas) is completely obliterating every trace of this sound card and starting up again fresh.

My advice is to start all over again.  I think these problems come from the sequence that the SM Bus drivers get installed.

Get the drivers for your Motherboard for windows 7 if they have em, for Vista if they don't
Disable your onboard sound in BIOS.
Clean Install.
Install Drivers: Chipset/SMbus. SATA/Raid/Video
Enable sound in BIOS install Sound
Then Ethernet and Misc
in that order

I too have had the hex in all OS's with the damned sound to the point where I sometimes just say the hell with it and put in a cheap sound card and turn it loose.

I think that after a faulty install the sound drivers take up an conflicting address and from that point on they won't work unless you can find every entry in the registry and delete them.

I was worried that may be the case.  Oh well, if it is I haven't installed anything on Win7 yet (no point with no sound) and the Win7 installer is the quickest damn OS install I've ever done.

Latest driver directly from Realtek here:
http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=14&PFid=24&Level=4&Conn=3&DownTypeID=3&GetDown=false

R2.36 came out today actually. Get the executable(5th down).

1) Remove current Realtek driver and reboot. No sound.
2) Shut down and go into your BIOS and disable onboard sound then boot up again.
3) Shut down and re-enable onboard in BIOS and let Windows "find new hardware"...cancel all pop up windows then install the R2.36 drivers and reboot once more.
4) setup hopefully

I have had the same problem with my Toshiba laptop.  It has a Conexant HD sound but I cannot get the sound to work.  I have tried every known work around and I am seriously considering putting Vista back on it.

Attempted to no avail

Is this your first time using a Windows newer than XP? If yes, then you may or may not already know this:

Vista and Win7 use a totally different method to do sound on the O/S than XP did. For example EAX will no longer work, nor is it selectable anymore in games that had it(add-on sound card can still do it w/software). And surround sound games using the older XP style will also not work in surround, newer games work fine because they conform to the new standard.

Additionally, you will now have 2 separate sources for sound output when right clicking the sound icon at the bottom right of your desktop(not the Realtek icon, the Windows sound icon). Right click it and select Playback. You should see 2 choices: Speakers, and Realtek Digital Output. Make sure you configure(not properties) for the type of speakers you have. You will only be able to do Properties for the Digital Out, can't configure.

The "Speakers" choice uses your analog 3.5mm minijacks. The Realtek Digital Output is for your digital optical or coaxial cable only. Depending on what you are listening to, you have to change back and forth just like a receiver tuners input. You use "Speakers" for all Windows stuff, games, etc. Use "Realtek Digi Out" for movies or digital stuff.

If you knew this, sorry. But when I first switched to Vista I couldn't figure out the problem until I discovered there were now 2 outputs from the sound icon.

Solved!

Win7 changed from one set of jacks to another - a set that I had disabled in Windows XP.

I feel like an idiot

Thought you tried all the jacks already?

Before my last driver update.
No idea if that had any impact.

But the last time I ran into this jack I got no sound output.  Be that because of a driver, because the sound card felt like being a bitch, because I didn't push it in all the way - one of those is the reason I didn't get sound.