I'm running an ASUS P8Z68-V Pro mobo with Realtek HD sound.
I built this computer back in December of last year and it was working great until about four days ago.
First I got a blue screen and then no signal from my vid card. I have an XFX Radeon 6950 card. I ended up trying a number of things to get it working again and finally reinstalled windows 7.
Everything was working good again until today when it crapped out with what I can only assume was a similar situation. I didn't see it blue screen, I just came back to my computer and there was no signal to my monitor. This time, however, I also had lost sound.
When I plug my headphones into the front jack, I get a slight fuzzy sound almost like the ocean, but only in my left earphone, and no actual audio from the computer. The other strange thing is that Realtek thinks I'm plugging my mic in. I've checked all the plugs and nothing is unplugged.
So I tried plugging in my speakers into the rear jack and I get roughly the same result. Fuzzy noise, no audio. I figured, oh well, might as well reformat again and see if that fixes it. It didn't. Right off the bat it went back to the fuzzy noise.
I've tried uninstalling Realtek and installing the latest driver. I've tried installing new chipset drivers. I'm really at a loss for words and I'm out of ideas.
The best I can come up with is that the mobo is shorting out. First the vid card, now the audio.
It could be that the crash/sound problem is a result of a failing Realtek sound chip. Try disabling the on-board sound in BIOS and see if you can use the system without it crashing. If you have a monitor with speakers, you may be able to temporarily switch your audio output to the HD 6950. If all is well, you can add a discrete sound card for your audio.