Computer Freezing Need Help

I have been trying to fix this problem for like 3 weeks now and I believe it is my power source. I recently bought a new H8-1212 HP Pavillion computer and added a few more things to it for gaming. However I never added a different power source because I never thought of it at the time. About every 5-10 mins my computer will freeze or lock up. Sometimes it hard freezes and I have to manually shut down and sometimes I am able to ctrl+alt+del and use the task manager. I also sometimes get the error, "AMD Display Driver has stopped responding and has successfully recovered". My current PSU is 460W max and 100-240V. My specs are:

8GB of memory/ram
AMD FX(tm)-6120 Six-Core Processor
AMD Radeon HD 7700 series graphics card
Windows 7 64-bit
DirectX 11