Power Supply Causing Static in Audio

Last year, I purchased a 500W Rocketfish power supply from Bestbuy when I upgraded my graphics card. They had a very bad selection and I didn't want to purchase online. Ever since, I have had problems with my audio when I start to play games. After about 30 minutes into my game or 30 minutes into watching videos online after booting up, the audio starts to become filled with static and it gets worse over time. My internet even disconnected when I have a wired connection. However, when I restart my computer, the problem goes away entirely.

My specs are...

Intel Core i7 860 @ 2.80GHz
Lynnfield 45nm Technology

8gb of Ram

Dell Inc. 0X231R motherboard

AMD Radeon HD 6770 graphics card (1600x900 resolution)

500GB Seagate hard drive


Is 500W enough to power all of this? Is my power supply at fault for my problem? What is the appropriate wattage for my system? what PSU's do you recommend?