I`m not certain your PSU is the cause of your problem. It sounds like software is hogging the resource. Open `Task Manager` and see what CPU usage you have and identify what is using it.
I am told that Hiper PSUs are not the best in the world, but mine is fine and 580W seems plenty for your PC. If you fit a larger (700W) PSU the PC will only draw what it needs to function so you wont do any damage and Arctic Power have a good name.