BleepingComputer.com: MOBO beeps when doing something graphics intensive

Mobo making error noise while using my HTPC every so often. So far, I noticed it when:

• Playing Deus Ex (low settings 1024 tops)
  
• Watching TV through WMC (HD Homerun Prime)

Here's a vid I uploaded to YT when watching TV through WMC:


I doubt it's an overheating issue, in this particular case, the PC was on for 20 minutes and is well ventilated, I leave it in the open.

Deus Ex was the only game I tried, and so far, only watched tv 1 time, all other times when using pc for normal functions (surfing, videos, music) no problems. The next day when I booted up the PC to watch TV, no beeping noise.

I've had motherboards that beep when using up/down/left/right arrow keys on web pages, when using OpenOffice or MS Works, and sometimes just typing text. I never could track the "problem" down, because everything kept running just fine.

Does your beeping only happen when the graphics card is under heavy load, or is it at other times as well?

Just because the case is well ventilated does not mean its not a heating issue, have you checked your temps to make sure its not overheating? For example, if the video card draws more power then the PSU can handle, the PSU will put out 3 times more heat then normal trying to keep up-and heat up the rest of the system. and what do you mean by left in the open-as in its not in a confined space, or is the panel open? often times, leaving the side panel open can cause more problems then it helps.

Leaving the side panel open, wrecks the airflow in the case.