EP45UD3R no audio

No guarantees here but that message usually implies you have a self sensing audio port by Realtek. It suggests to me that there is nothing plugged into the speaker plug on back of board. Try contol panel, sound, to see how it views your current speaker setup. Then go into Realtek HD Audio and see how thats configured for the audio. I'm guessing the port reassigned itself to a different plug or you may have plugged into one that is not configured to match speaker setup.

Assuming you have a 95 watt E0 step Q9550 (most likely - on the box, it will have sSpec SLB8V), on either the 1.0, or 1.1 revision boards, you need to have BIOS F3; if you have the 'energy saving' 65 watt Q9550S (and you'd likely know it - they're more expensive, and have sSpec SLGAE), either board will need F6 -

1.0 rev: http://www.gigabyte-usa.com/Support/Motherboard/CPUSupp...
1.1 rev: http://www.gigabyte-usa.com/Support/Motherboard/CPUSupp...

The BIOS for either rev board is the same; current is F11 here:

http://www.gigabyte-usa.com/Support/Motherboard/BIOS_Do...

Excellent GB BIOS flashing guide here:

http://forums.tweaktown.com/f69/bios-flashing-how-qflas...

Bilbat. I am having the same issues. how did you know it was the bios causing the problem?

His problem was the new processor - microcode for that stepping not handled by existing BIOS; is this a new rig, or was it once working OK? New case, maybe?

I just built a new rig with this mobo. I have a q9650 and windows 7 64 bit. It seems the sound works in 5.1 if the computer has been sitting powwered off. I startt it up it works but with in a few minutes it turns into a low muffled inausible sound. There is sound coming out but it is very muffled. I have tried everything other than the sound my new build is kick ass. I always thought it was best to have the latest bios? I am going to try this when I get home tonight. Can I ask you any questions if I still have problems with the realtek sound? Oooh. It also does the same thing if I disable onboard audio in the bios and use Sound Blaster X FI Gamer card. Thank you for getting back to me!!!

Oh bilbat. I forgot to ask. does hpet being disabled or enabled have anything to do with poor sound from 5.1? I have been reading that is is a multimedia streaming thing. I know for sure I have it disabled on my mobo right now.

I've always enabled HPET at 64-bit, and used it with both 32 & 64 bit systems (I boot nine OSs) - never had a problem traceable to it... The usual problem is (inordinately)high DPC (deferred procedure call) latencies; it is usually caused by: drivers written by dipsticks, ring zero program components (which work like drivers - for example, SlySoft's AnyDVD, and most 'iso file mounters' use ring zero to do their magic) written by the same; way too many useless programs loading in the 'background' installed without your knowledge or permission - iTunes is a good example! Typically it will cause skipping or 'popping' in audio streams, artifacts and audio dropouts in video streams - I've never heard of it kind of 'mushing out' the sound, but it'd still be the first thing I'd check; there's a tool for checking it here:
http://www.thesycon.de/deu/latency_check.shtml
Capture the resultant screen and post it - I'll help with diagnosis...

BTW, if you've never captured and posted screens, there's a (longish, but thorough) tutorial here:
http://www.tomshardware.com/forum/264718-30-capture-pos...