Windows 7600 Ultimate, no sound at all.

I've just yesterday installed Windows 7 Ultimate 7600 and everything's been fine apart from one thing. There is no sound whatsoever.

I've tried:

• Downloading ALL the availible Windows Updates including optional ones
• The drivers from the DVD which came with my motherboard.
• The drivers from the the website of my motherboard.
• The latest Realtek drivers from the Realtek Website
• The latest ATI catalyst drivers

None have worked.

My headphones are simply not detected, and the only audio device 'Digital Audio (HDMI)' is shown as not plugged in. I've tried plugging the headphones into the front panel, rear panel and there is still no response at all, as if they simply don't exist.

I'm at a bit of a loss as what I could possibly do, I know it's not my headphones that are at fault since I've just tested them on another system and they're fine.

Any help would be greatly appreciated, this is really really annoying, I've posted all my system specs.

Thanks in advance