29.80 Detonators are actually leaked drivers. Try and find the 29.42's. I have had problems with the official 30.82's too. Get them to work, and they work so wonderfully. Heres my tips with odd Geforce cards (Your card is top notch stuff

)
1. Totally delete your drivers and reinstall them. (Detonator Destroyer)
2. Try a modified set of Detonator Drivers (Search for Omega Dets 11.82, I use em)
3. Download latest Via 4-in-1 Drivers (Solves lotta probs)
4. Use standard clock settings on everything if you overclock.
5. Buy a new soundcard to fix the problem
As for your 300 Watt, dont get a stronger one. I have a 300 Watt PSU and everything runs fine on my rig. (1Ghz P3, VisionTek Geforce4 TI 4200, 2 HD's, 2 CD-ROM, SB Live! Value, fans up the wazoo

)