If your PSU has a voltage selector switch on back to choose between 115V and 230V or it has active PFC, then you can use your PSU in Australia. BTW I read that it's a good idea to set that switch to 230V and cover it with tape so it won't accidentally be flipped to 115V and cause the PSU to burn up.
I saw only one PSU that had to be used at 100-125V AC, but it was a Lite-On OEM model. Watch out for this if you have an OEM model, that is a PSU that was included with a major brand computer or bought on the surplus market.