I'm having almost the exact same problem.
I have found that two games, Far Cry and Half Life 2 seem to have the same issue with my system. BOTH video and audio freezes for a few seconds (anywhere from 3-30 seconds), then everything returns to normal and repeats. What is strage is that Doom 3 and Sims 2 run VERY SMOOTH with NO freezing.
I've gone through all the usual checks, all drivers are up to date, hard drive defraged to be sure, checked BIOS, etc. It would lead me to think it was the card or something else, but Doom 3 runs like crazy and is so smooth it looks like a movie. I can take it up to HIGH settings for everything and be just fine with room to spare. Also, I have patched Far Cry with 1.3 and even called their support. All they said was my video card wasn't out then so they couldn't test the game with it (BFG Gforce 6800 Ultra OC ). So, I'm wondering what the deal is here? My system BIOS and motherboard chip set drivers are all current as well. I'm not overclocking anything either.
While the BFG video card ships FACTORY overclocked and checked, I've heard others have issues like this that didn't have this card so I don't think it's at fault. Especially given Doom 3 is OK.
Any thoughts on this? Does anyone have a rig with specs like mine that may be able to help? It would be helpful to hear from someone that's built a PC like this or maybe an Alienware/Falcon PC like it. I could sure use some input on this because I've just about exhausted all the usual.
Thanks,
Jeff
Specs:
Case: Coolermaster - Model ATC110
Custom Artwork: American flag, Liberity Bell and other done by Smooth Creations (VERY NICE and HIGHLY recommended).
Power: PC Power and Cooling 510 Watt Turbo.
CPU: AMD Athlon 64 FX-53.
Motherboard: MSI K8N Neo2 nForce3.
Video Card: BFG nVidia GeForce 6800 Ultra OC.
Sound: Sound Blaster Audigy 2 ZS Platinum Pro with external breakout box.
Memory: 2 GIG of Corsair TWINX1024-3200XLPRO.
Primary Storage: 2 Western Digital Raptor 74GIG.
Optical: Pioneer Model DVR108 - Dual Layer DVD+/-RW.
Mouse: Logitech Laser - Model MX1000.
Keyboard: Microsoft Natural.